In support of the Choosing Wisely campaign: Perceived higher risk leads to unnecessary imaging in accelerated partial breast irradiation?

Accelerated partial breast irradiation (APBI) is an increasingly utilized modality for early stage breast cancer as part of breast conservation therapy (BCT). There remains concern regarding local recurrence, requiring more frequent post-radiation surveillance imaging. The purpose of this study is to determine clinical significance of frequent surveillance in this perceived higher risk population. Patients treated at a community academic medical center from 2005 to 2013 with partial breast radiation were retrospectively identified. All patients were treated with lumpectomy followed by balloon based APBI. Diagnostic, clinical, radiographic, and outcomes data were collected. One hundred and sixty-nine patients were identified. Median age at time of diagnosis was 63. Stage was 0, I, and II in 27%, 64%, and 9%, respectively. Most patients had pure invasive ductal cancer. Ninety-two percent and 99% of patients had imaging performed by 6 and 12 months (± 3 months) respectively. Median interval between end of radiation and first image, and subsequent 3 images were 6, 6, 9, and 12 months, respectively. Median follow-up was 49 months for all patients (range 7-106). Six patients experienced local recurrence: 4 invasive, all clinically detected, and none within the first 2 years. One patient had mammographically detected recurrent ductal carcinoma in situ. No mammographic images within the first year lead to diagnosis of recurrent cancer. APBI via balloon base brachytherapy offered women excellent locoregional control rates. Frequent mammographic surveillance did not result in increased detection of early recurrent disease. The result of our study are in line with the Choosing Wisely campaign recommendations to perform no more than annual follow-up for women who have completed radiation as part of BCT, with first imaging done at 6-12 months. We recommend mammographic surveillance be performed no more frequently than annually, with first image after BCT to be done 12 months from completion of radiation.

Foaming Betadine Spray as a potential agent for non-labor-intensive preoperative surgical site preparation.

BACKGROUND: The Centers for Disease Control and Prevention's (CDC) National Healthcare Safety Network (NHSN) report published in 2009 shows that there were about 16,000 cases of surgical site infection (SSI) following ~ 850,000 operative procedures making SSI one of the most predominant infection amongst nosocomial infections. Preoperative skin preparation is a standard procedure utilized to prevent SSIs thereby improving patient outcomes and controlling associated healthcare costs. Multiple techniques/ products have been used for pre-operative skin preparation, like 2 step scrubbing and painting, 2 step scrubbing and drying, and 1 step painting with a drying time. However, currently used products require strict, time consuming and labor-intensive protocols that involve repeated mechanical scrubbing. It can be speculated that a product requiring a more facile protocol will increase compliance, thus promoting a reduction in SSIs. Hence, the antimicrobial efficacy of a spray-on foaming formulation containing Betadine (povidone-iodine aerosol foam) that can be administered with minimum effort is compared to that of an existing formulation/technique (Wet Skin Scrub). METHODS: In vitro antimicrobial activities of (a) 5% Betadine delivered in aerosolized foam, (b) Wet Skin Scrub Prep Tray and (c) liquid Betadine are tested against three clinically representative microorganisms (S. aureus, S. epidermidis and P. aeruginosa,) on two surfaces (agar-gel on petri-dish and porcine skin). The log reduction/growth of the bacteria in each case is noted and ANOVA statistical analysis is used to establish the effectiveness of the antimicrobial agents, and compare their relative efficacies. RESULTS: With agar gel as the substrate, no growth of bacteria is observed for all the three formulations. With porcine skin as the substrate, the spray-on foam's performance was not statistically different from that of the Wet Skin Scrub Prep technique for the microorganisms tested. CONCLUSIONS: The povidone-iodine aerosolized foam could potentially serve as a non-labor intensive antimicrobial agent for surgical site preparation.

Utilization of Circulating Tumor DNA in the Surveillance Setting.

INTRODUCTION: National guidelines give recommendations regarding cancer surveillance follow-up. In many early staged cancers radiographic imaging and labs are not routinely recommended unless patients are symptomatic. This can cause a gap in care because commonly when patients present symptomatically, they have progressed and transitioned to later-stage cancer. This study demonstrates how circulating tumor DNA (ctDNA) can be used alongside current guidelines to help screen patients for recurrence in the surveillance setting. METHODS: A retrospective chart review was performed. Fifty-five charts were reviewed of patients who received ctDNA testing drawn in follow-up after their primary tumor or metastatic disease was rendered surgically or radiographically disease-free. A customized signature profile, using the sixteen most prevalent genomic markers from a patient's primary tumor or biopsy, is developed by whole-exome sequencing. Serial blood draws are then drawn to assess for specific DNA markers using polymerase chain reaction (PCR) assays. RESULTS: Fifty-five charts were reviewed in patients who had stage I-III breast, pancreatic, melanoma, and colorectal cancer. Of the fifty-five, a total of seven had a positive test. Of the seven positive tests, six patients were found to have recurrent/metastatic disease. One positive test was performed four weeks postoperatively but by the second draw ten weeks postoperatively had non-detectable ctDNA. The remaining forty-eight patients had non-detectable ctDNA levels and to date have not had any evidence of recurrence based on standard follow-up guidelines. CONCLUSION: The utilization of ctDNA in the surveillance setting can be used to help detect recurrence in the surveillance setting.

Mucocele-like Lesions of the Breast.

Mucocele-like lesions of the breast (MLL) are believed to be due to mucinous ducts extruding their contents into the surrounding stroma. MLLs are a rare entity usually identified by calcifications noted on routine screening mammography. Surgical excision has been recommended due to the propensity for these lesions to harbor atypical ductal hyperplasia (ADH) or malignancy. A 44-year-old female patient presented to the breast center after undergoing routine mammography which showed a group of coarse appearing microcalcifications in the outer third of the breast. After further workup, a core needle biopsy was obtained with pathology showing benign breast tissue with acellular stromal mucin pools containing dystrophic calcifications. The patient underwent surgical excision with final pathology revealing ductal carcinoma in-situ and ADH with prominent mucin production throughout the stroma.

Mammography as a screening tool for diabetes.

BACKGROUND: This large retrospective study investigates the relationship between breast arterial calcifications (BAC) identified on screening mammography and the presence of DM, thereby evaluating the utility of screening mammography as an additional screening tool for diabetes. MATERIALS AND METHODS: The screening mammograms of 1000 women were prospectively evaluated for BAC; women with a prior history of DM or CAD were excluded. This screening group was compared with all diabetic women who had undergone routine mammographic screening at our institution. The relationship between BAC and DM was statistically evaluated. RESULTS: Of the 1000 women prospectively evaluated, we identified 819 women without a history of either DM or CAD. Of these 819 women, mammographic BAC was identified in 86 for a baseline incidence of BAC in our screening population of 10%. We identified 790 diabetic women who had undergone screening mammograms at our institution, and BAC was identified in 288 (36.45%). The incidence of vascular calcifications was significantly higher in the DM group (P<0.001) than in the screening group, irrespective of age. Stratifying by age group, we identified a significant relationship between BAC and DM (CMH test P<0.001). The estimated odds ratio of having diabetes if BAC is present is compared with BAC being absent is 4.5 (95% confidence interval (3.2, 6.1). CONCLUSIONS: BAC identified on routine screening mammography can identify a group of women at high risk for diabetes. Prospective studies are currently underway at our institution to confirm the utility of screening mammography as a screening tool for diabetes.

Detection of melanoma cells in vitro using an optical detector of photoacoustic waves.

BACKGROUND AND OBJECTIVE: Circulating tumor cells have been shown to correlate positively with metastatic disease state in patients with advanced cancer. We have demonstrated the ability to detect melanoma cells in a flow system by generating and detecting photoacoustic waves in melanoma cells. This method is similar to flow cytometry, although using photoacoustics rather than fluorescence. Previously, we used piezoelectric films as our acoustic sensors. However, such films have indicated false-positive signals due to unwanted direct interactions between photons from the high laser fluence in the flow system and the film itself. We have adapted an optical detection scheme that obviates the need for piezoelectric films. STUDY DESIGN/MATERIALS AND METHODS: Our photoacoustic system comprised a tunable laser system with an output of 410-710 nm with a pulse duration of 5 nanoseconds. The light was delivered by optical fiber to a glass microcuvette that contained saline buffer suspensions of melanoma and white blood cells. We used a continuous HeNe laser to provide a probe beam that reflected off of a glass and water interface in close proximity to the microcuvette. The beam was detected by a high-speed photodiode. When a photoacoustic wave was generated in the microcuvette, the wave propagated and changed the reflectance of the beam due to index of refraction change in the water. This perturbation was used to detect the presence of melanoma cells. RESULTS: We determined a detection threshold of about one individual melanoma cell with no pyroelectric noise indicated in the signals. CONCLUSIONS: The optical reflectance method provides sensitivity to detect small numbers of melanoma cells without created false-positive signals from pyroelectric interference, showing promise as a means to perform tests for circulating melanoma cells in blood samples.

Integration of a 31-Gene Expression Profile Into Clinical Decision-Making in the Treatment of Cutaneous Melanoma.

BACKGROUND: The practice of utilizing gene expression profile (GEP) for the evaluation and treatment of cutaneous melanomas has been found to predict the risk of sentinel-node metastasis and recurrence. Information obtained from this assay has been used to determine clinical decision-making, including serving as an indication for sentinel lymph node biopsy and also for the intensity of screening measures. METHODS: Herein we present our early experience in utilizing 31-GEP in intermediate melanomas and its effect on clinical management. A retrospective review was conducted of patients who had undergone treatment for melanoma whose tumors had been subjected to 31-GEP. Additionally, patient characteristics, attributes of the original tumor biopsied, findings on final pathology, and procedures performed were evaluated. RESULTS: 31-GEP stratified patients into 4 groups; groups 1A and 1B are considered low risk of metastasis or recurrence, while 2A and 2B are considered high risk. Over the study period, 31-GEP was conducted on 26 cutaneous melanoma patients. Testing and treatment data are available for 23 of these patients. Eleven patients were found to be low risk (9 as 1A, 2 as 1B), 12 were found to be high risk (4 as 2A, 8 as 2B). Decision-making was altered such that sentinel lymph node biopsy was omitted in 2 cases in which the patients were found to be low risk with age >65 years. DISCUSSION: In 8 cases of node-negative disease in genetically high-risk patients, surveillance measures were augmented with positron emission tomography/computed tomography. Utilization of 31-GEP is ongoing at our institution.

Rapid and label-free detection of breast cancer biomarker CA15-3 in clinical human serum samples with optofluidic ring resonator sensors.

Sensitive and specific detection of breast cancer biomarker CA15-3 in human serum is an important step toward successful evaluation of clinical treatment and prediction of breast cancer recurrence. In this work, we developed an optofluidic ring resonator (OFRR) sensor and the corresponding sensing protocols for label-free CA15-3 detection without any additional signal amplification steps. Nonspecific serum protein adsorption was minimized with effective surface blocking methods. The sensor performance for CA15-3 detection was first characterized in phosphate-buffered saline (PBS) buffer and in fetal calf serum. Then the potential use of the OFRR as a simple clinical laboratory testing device for breast cancer diagnostics was tested by measuring the CA15-3 level in clinical human serum samples, and the results were compared with those of standard clinical lab tests. It was found that the OFRR was capable of detecting approximately 1 unit/mL CA15-3 in both PBS buffer and diluted serum within approximately 30 min. Our work marks the first demonstration of the optical ring resonator biosensor in real clinical applications that features low cost, simple detection procedures, rapid response time, low sample consumption, and high specificity.

Plantar fibromatosis masquerading as metastatic melanoma.

We present the evaluation and treatment of a 59-year-old male with a medical history significant for multiple recurrences of malignant melanoma. The patient was found to have increased focal uptake of his right foot on fluorodeoxyglucose positron emission tomography. Given the patient's clinical history, the increased uptake was suspected to be recurrence of his disease. The nodule was surgically excised and was later pathologically diagnosed as benign plantar fibromatosis. To our knowledge, only one other case report of plantar fibromatosis demonstrating increased fluorodeoxyglucose positron emission tomography uptake exists. Given the distinct prognostic differences between plantar fibromatosis and recurrent malignant melanoma, clinicians should be aware of the possibility of such false-positives with fluorodeoxyglucose positron emission tomography during oncologic surveillance.

Comparison of Call-Back Rates between Digital Mammography and Digital Breast Tomosynthesis.

The effect of mammographic screening on the natural history and evolution of breast cancer treatment cannot be overstated; however, despite intensive and resource consuming screening, advanced breast cancer is still diagnosed frequently. The development of three-dimensional mammography or digital breast tomosynthesis (DBT) has already demonstrated greater sensitivity in the diagnosis of breast pathology and effectiveness in identifying early breast cancers. In addition to being a more sensitive screening tool, other studies indicate DBT has a lower call-back rate when compared with traditional DM. This study compares call-back rates between these two screening tools. A single institution, retrospective review was conducted of almost 20,000 patient records who underwent digital mammography or DBT in the years 2016 to 2018. These charts were analyzed for documentation of imaging type, Breast Imaging Reporting and Data System 0 status, call-back status, and type of further imaging that was required. Charts for 19,863 patients were reviewed, 17,899 digital mammography examinations were conducted compared with 11,331 DBT examinations resulting in 1,066 and 689 Breast Imaging Reporting and Data System 0 studies, respectively. Of the DM call-backs, 82.08 per cent were recommended for additional radiographic imaging and 17.82 per cent for ultrasound imaging. In the DBT group, only 39.77 per cent of call-backs were recommended for additional radiographic imaging and 60.09 per cent for ultrasound imaging. Our data suggest that DBT results in less call-back for additional mammographic images as compared with digital mammography. DBT may offer benefits over DM, including less imaging before biopsy, less time before biopsy, quicker diagnosis, and improved patient satisfaction.

Nuclear Factor-κB is Activated in Filter-Implanted Vena Cava.

BACKGROUND: Implantation of a retrievable vena cava filter (VCF) is an effective method for preventing pulmonary embolism. Retrieval of filters, however, may be difficult due to intimal hyperplasia and inflammation in the cava wall. The transcription factor nuclear factor-kappaB (NF-κB) plays an important role in regulation of numerous genes participating in the inflammatory and proliferative responses of cells. The present study was to determine whether VCF implantation resulted in activation of NF-κB in the venous neointima. METHODS: Filters were placed in vena cava (VC) in four swine for 30 days and then removed. Intimal specimens adhering to the filter struts were analyzed with reference to normal VC tissues. Immunohistochemical analyses were used to assess the NF-κB subunits p65 and p50 and the phosphorylated inhibitor of κB-α (phosphor-IκB-α) in the tissues. NF-κB DNA-binding activity was measured with enzyme-linked immunosorbent assay. RESULTS: As compared to normal VC tissues, the intimal tissues contained higher percentages of cell nucleus-located p65 and p50, and NF-κB DNA-binding activity. Elevated immunoreactivities of p65, p50 and phosphor-IκB-α were also present in the intima. CONCLUSION: The present study demonstrates for the first time that VCF implantation caused NF-κB activation in neointima. We further demonstrate the activation is at least partly due to phosphorylation of IκB-α. Our data suggest that NF-κB activation would significantly contribute to development of intimal hyperplasia and inflammation in filter-inserted vena cava walls. NF-κB might be a therapeutic target for inhibiting filter-induced neointima and improving filter retrieval.

A 12-Year Single-Institution Experience with Accelerated Partial Breast Irradiation.

Accelerated partial breast irradiation (APBI) using the implanted brachytherapy device MammoSite® was approved for routine use by the Food and Drug Administration in 2002. The American Society of Breast Surgeons MammoSite® Breast Brachytherapy Registry served as a guideline for our institution to begin offering this treatment in 2005. This report reviews our available data to provide an analysis of patient outcomes over 12 years of use at a single institution. A retrospective review was conducted of records of 150 patients who underwent APBI or attempted APBI after breast-sparing surgeries between 2006 and 2017. These charts were analyzed for documentation of patient age, cancer stage, incidence of recurrence, and posttreatment complications. Of the patients evaluated, 99 per cent (149/150) completed treatment. The median time since treatment completion is now 8.9 years. One hundred eleven patients (74% ) are now greater than five years posttreatment. Ipsilateral breast recurrence was found in 2.7 per cent of patients (4/149), and 1.3 per cent of patients (2/149) developed new primary breast tumors. Acute complications, mostly skin erythema (21%), were uncommon and self-limited. Subacute effects were generally fibrosis (13%) and mild local pain (9.4%). APBI for breast cancer after breast-conserving surgery continues to be used at our institution for select patients with good outcomes. Local control and toxicity are similar to that reported in the literature. Five-year local recurrence rates compare favorably with national trials. Occasional complications included fibrosis, persistent pain, and skin irritation.

Analysis of biomolecule detection with optofluidic ring resonator sensors.

We theoretically and experimentally analyze the biomolecule detection capability of the liquid core optical ring resonator (LCORR) as a label-free bio/chemical sensor. We first establish a simple and general linear relationship between the LCORR's bulk refractive index sensitivity (BRIS) and its response to molecule deposition onto the surface, which enables us to easily characterize the LCORR sensing performance. Then, biosensing experiments are performed with bovine serum albumin (BSA) and LCORRs of various BRISs. The experimental results are in good agreement with the theoretical prediction. Further analysis shows that the LCORR is capable of detecting BSA below 10 pM with sub-picogram/mm2 mass detection limit.

Mammography as screening for coronary artery disease.

Coronary artery disease (CAD) is the leading cause of death in American women. Screening mammograms are recommended for women starting at age 40 for the early detection of breast cancer. An additional benefit of this routine screening tool may be to detect breast arterial calcifications (BAC) as a possible sign of CAD. The purpose of this study was to determine further the relationship between mammographically detected BAC and CAD. The medical records of 44 women who had undergone coronary artery bypass grafting at our institution over 5 years were reviewed. These mammograms were examined for evidence of BAC. For all women included in the study, 18 of 44 (41%) had evidence of BAC on screening mammogram. This was statistically significant (P < 0.0001) compared with the prevalence of BAC reported in the general population in previous studies. Most were also overweight (61.1%), had hypertension (88.8%), and hypercholesterolemia (55.5%). This is the first study to look at the direct correlation between patients with known CAD requiring revascularization and BAC. Perhaps women with BAC seen on screening mammography should undergo further workup for CAD, with the potential benefit of early intervention.

Mammography as a screening tool for peripheral vascular disease.

BACKGROUND: Peripheral vascular disease (PVD) is a progressive and debilitating disease often diagnosed only when patients become symptomatic. Currently there are no widespread screening tests available for the early detection of PVD. Patients with diabetes and coronary artery disease are known to have a higher incidence of PVD. Prior studies have indicated that benign vascular calcifications seen on routine screening mammogram are more prevalent in women with diabetes and coronary artery disease. The same association has not been shown for women with PVD. The purpose of this study was to identify an association between benign vascular calcifications identified on mammography and PVD. If such an association exists then screening mammography, already widely used as a screening tool for breast cancer, may identify women at high risk for PVD. METHODS: To determine the incidence of vascular calcifications in our general screening population we prospectively evaluated consecutive routine screening mammograms for the presence of benign vascular calcifications. We then identified a population of women with PVD by using a computerized database maintained by the Division of Vascular Surgery. The population of women identified with PVD was categorized further to identify those women who had received routine screening mammogram within our hospital system. These mammograms were reviewed retrospectively with particular attention to the presence of vascular calcifications. All mammograms were reviewed by our dedicated mammographers. Statistical analysis of the study group using the chi-square test was performed to determine the association of PVD and mammographic vascular calcifications. RESULTS: Prospective evaluation of 645 women undergoing consecutive routine screening mammography identified 123 (19%) with benign vascular calcifications. By using our PVD computerized database between the years 2002 and 2004 we identified 763 women with PVD. Of this group only 121 (15%) had undergone a routine screening mammogram in our hospital system. These mammograms were reviewed retrospectively by the same group evaluating the screening mammograms. On evaluation vascular calcifications were identified in 42% (51 of 121) of these women with PVD. Statistical analysis was performed using the chi-square test, odds ratio, and relative risk. A highly significant association was identified between PVD and the presence of mammographic vascular calcifications (P > .001). With a confidence interval of 95% the presence of benign vascular microcalcifications on routine screening mammogram identifies a significant risk for PVD with an odds ratio of 3.06. We showed through our analysis that women with calcifications are 2.19 times more likely to have PVD if microcalcifications are present. By using vascular calcifications identified on screening mammography as a means to identify women with PVD the sensitivity and specificity are 42% and 80%, respectively. The positive predictive value and the negative predictive value are 29% and 88%, respectively, with an accuracy of 75%. CONCLUSIONS: This initial study indicates that the presence of vascular calcifications identified on routine screening mammogram is significantly higher in women with PVD and the lack of vascular calcifications on screening mammography correlates well with a negative history of PVD. We have identified a significant association with PVD and vascular calcifications in our patient population. Further studies are indicated to determine if screening mammography may become a widespread inexpensive screening tool to identify women at risk for PVD. Additional studies are underway at our institution to evaluate the association of PVD, diabetes and coronary artery disease, and vascular calcifications identified on routine screening mammography.

Impact of a surgical oncologist on general surgery residency training program.

BACKGROUND: To assess the impact of adding a surgical oncologist to our faculty we examined the operative experience in our program before and after the addition. METHODS: Operative case numbers reported to the American Board of Surgery over a 10-year period were analyzed. This time period encompassed 5 years before and after the addition of a surgical oncologist to our faculty. All defined category case numbers were examined using t test analysis. Significance was defined as a P value of less than 0.05. RESULTS: The overall caseload increased in the time period after the faculty addition. There was a statistically significant increase in skin/soft tissue, breast, esophagus, small intestine, large intestine, live, spleen, and endocrine cases. No statistical significance was seen in head/neck, stomach, pancreas, and biliary cases. CONCLUSIONS: The addition of a surgical oncologist to our faculty coincides with a statistically significant increase in areas of skin/soft tissue, breast, esophagus, small intestine, large intestine, liver, spleen, and endocrine. Other areas not statistically significant may reflect referral patterns or this particular oncologist's preferences of practice.

Radio-frequency ablation of large, nonresectable hepatic tumors.

Patients with nonresectable hepatic metastases who are not treated survive an average of 6 months. We report our experience with radio-frequency ablation (RFA) of nonresectable hepatic tumors 4 cm or greater in size. A retrospective chart review of all patients undergoing RFA of hepatic tumors 4 cm or greater from October 1, 1999, through August 31, 2002, was performed. Thirty-six patients were identified who underwent RFA of tumors 4 cm or greater. There were a total of 81 tumors ablated in the 36 patients. Twenty patients underwent RFA only; seven patients received RFA plus a wedge resection. Five patients were treated with RFA followed by chemoembolization. Two patients underwent RFA plus placement of a hepatic artery infusion pump. The median tumor size was 5 cm (range, 4-14 cm). Median patient follow-up was 26 months (range, 1-54 months). Patients with metastatic colon cancer had the longest median survival of 28 months (range, 1 and 48 months). The survival of primary hepatocellular carcinoma was worse with a median survival of 20 months (range, 1-36 months). At last follow-up, 11 (30%) of the patients remain alive and disease free. There were no perioperative deaths and one intraoperative complication. In our experience, RFA of larger tumors is effective and safe. Tumor size should not be an absolute contraindication to RFA of nonresectable hepatic tumors.

Surveillance recommendations in reducing risk of and optimally managing breast cancer-related lymphedema.

Breast cancer survivors are at increased risk for the development of breast cancer-related lymphedema (BCRL), a chronic, debilitating, and disfiguring condition that is progressive and requires lifelong self-management of symptoms. It has been reported that over 40% of the 2.5 million breast cancer survivors in the United States may meet the criteria for BCRL during their lifetimes. Ongoing surveillance, beginning with pre-operative assessment, has been effective in identifying subclinical lymphedema (LE). A prospective model for surveillance is necessary in order to detect BCRL at an early stage when there is the best chance to reduce risk or slow progression. Physical methods for monitoring and assessment, such as circumferential arm measures, perometry, bioimpedance; exercise programs; prophylactic and early-intervention compression garments; and referral for complete decongestive therapy are all interventions to consider in the development of a BCRL surveillance program. In addition, supportive-educative programs and interactive engagement for symptom self-management should also be implemented. The importance of interdisciplinary collaboration is integral to the success of an effective personalized medicine program in breast cancer-related lymphedema surveillance.

Gold nanoparticle mediated detection of prostate cancer cells using photoacoustic flowmetry with optical reflectance.

The presence of circulating tumor cells in the bloodstream has been correlated with disease state in cancer patients. While we have successfully exploited melanin, the natural light absorber in melanoma cells, to induce photoacoustic waves for tumor cell detection, non-pigmented tumor cells do not have sufficient optical contrast for such a method. For example, breast, prostate and lung cancers lack intrinsic pigmentation and thus do not generate photoacoustic waves. In order to induce optical contrast in non-pigmented cancer cells, we have attached gold nanoparticles to a prostate cancer cell line. This optical absorption will enable us to detect such cells in a photoacoustic flowmeter designed to find circulating tumor cells in blood samples. We tested a prostate cancer cell line, PC-3, by tagging them with gold nanoparticles. We determined the photoacoustic response over the wavelengths 470-570 nm to identify the absorption peak. We then determined the response from serial dilutions of PC-3 cells suspended in saline. Finally, we showed photoacoustic response from PC-3 cells suspended among white blood cells in the flow meter to demonstrate our ability to detect single cells under flow.

Detection of circulating melanoma cells in human blood using photoacoustic flowmetry.

Detection of circulating tumor cells (CTC's) in human blood and lymph systems has the potential to aid clinical decision making in the treatment of cancer. The presence of CTC's may signify the onset of metastasis, indicate relapse, or may be used to monitor disease progression. A photoacoustic flowmetry system was designed and tested for detecting circulating melanoma cells (CMC's) by exploiting the broadband absorption spectrum of melanin within CMC's. The device was tested on cultured melanoma cells in saline suspension and in a Stage IV melanoma patient. The device showed a detection threshold of a single melanotic melanoma cell from culture. Transient photoacoustic events were detected in a sample derived from a Stage IV melanoma patient that corresponded to particles passing through the laser beam path, indicating the presence of single melanoma cells in the human circulatory system.