Platinum-based regimens versus cetuximab in definitive chemoradiation for human papillomavirus-unrelated head and neck cancer.

For patients ineligible for cisplatin with definitive radiotherapy (CP-CRT) for locally advanced head and neck squamous cell carcinoma (LA-HNSCC), concurrent cetuximab (C225-RT) is a popular substitute. Carboplatin-based chemoradiation (CB-CRT) is another option; however, relative efficacies of CP-CRT, CB-CRT and C225-RT are unclear, particularly in the human papillomavirus (HPV)-unrelated population. We identified 316 patients with stage III-IVB cancers of the oropharynx (24.7%), larynx (58.2%) and hypopharynx (17.1%) undergoing definitive C225-RT (N = 61), CB-CRT (N = 74) or CP-CRT (N = 181). Kaplan-Meier and cumulative incidence functions were generated to estimate overall survival (OS), locoregional failure (LRF) and distant metastasis (DM). Cox proportional hazards were used to determine the association of survival endpoints with clinical characteristics. Respectively, 3-year cumulative incidences for CP-CRT, CB-CRT and C225-RT were: LRF (0.19, 0.18 and 0.48, p ≤ 0.001), DM (0.17, 0.12 and 0.25, p = 0.32). Kaplan-Meier estimates for 3 year OS were: CP-CRT: 71%; CB-CRT: 59% and C225-RT: 54%; p = 0.0094. CP-CRT (hazard ratio [HR] 0.336; 95% confidence interval [CI] 0.203-0.557, p < 0.01) and CB-CRT (HR 0.279; 95% CI 0.141-0.551, p < 0.01) were associated with reduced hazard for LRF on multivariable analysis. CP-CRT (HR 0.548; 95% CI 0.355-0.845, p < 0.01) and CB-CRT (HR 0.549; 95% CI 0.334-0.904, p = 0.02) were associated with a reduced hazard for death on multivariable analysis. Propensity matching confirmed reduced hazards with a combined CP/CB-CRT group compared to C225-RT for LRF: HR 0.384 (p = 0.018) and OS: HR 0.557 (p = 0.045) and CB-CRT group compared to C225-RT for LRF: HR 0.427 (p = 0.023). In conclusion, CB-CRT is an effective alternative to CP-CRT in HPV-unrelated LA-HNSCC with superior locoregional control and OS compared to C225-RT.

Plasma-based biomaterials for the treatment of cutaneous radiation injury.

Cutaneous wounds caused by an exposure to high doses of ionizing radiation remain a therapeutic challenge. While new experimental strategies for treatment are being developed, there are currently no off-the-shelf therapies for the treatment of cutaneous radiation injury that have been proven to promote repair of the damaged tissues. Plasma-based biomaterials are biologically active biomaterials made from platelet enriched plasma, which can be made into both solid and semi-solid forms, are inexpensive, and are available as off-the-shelf, nonrefrigerated products. In this study, the use of plasma-based biomaterials for the mitigation of acute and late toxicity for cutaneous radiation injury was investigated using a mouse model. A 2-cm diameter circle of the dorsal skin was irradiated with a single dose of 35 Gy followed by topical treatment with plasma-based biomaterial or vehicle once daily for 5 weeks postirradiation. Weekly imaging demonstrated more complete wound resolution in the plasma-based biomaterial vs. vehicle group which became statistically significant (p < 0.05) at weeks 12, 13, and 14 postmaximum wound area. Despite more complete wound healing, at 9 and 17 weeks postirradiation, there was no statistically significant difference in collagen deposition or skin thickness between the plasma-based biomaterial and vehicle groups based on Masson trichrome staining nor was there a statistically significant difference in inflammatory or fibrosis-related gene expression between the groups. Although significant improvement was not observed for late toxicity, plasma-based biomaterials were effective at promoting wound closure, thus helping to mitigate acute toxicity.

Telemedicine Use and Satisfaction Among Radiation Oncologists During the COVID-19 Pandemic: Evaluation of Current Trends and Future Opportunities.

PURPOSE: During the COVID-19 pandemic, telemedicine became an attractive alternative to in-person appointments. The role of telemedicine in patients who undergo frequent on-site treatment, such as radiation therapy, is unclear. The purpose of this study was to examine telemedicine use, physician satisfaction, and barriers to continued use in radiation oncology. METHODS AND MATERIALS: An anonymous, electronic survey was distributed to radiation oncologists internationally between June and October 2020. Respondents described demographic and practice characteristics, and a 5-point Likert scale assessed provider satisfaction, ease of use, and overall utility of telemedicine. Analyses include descriptive statistics and subgroup comparisons using the χ2 test and Fisher's exact test. RESULTS: The response rate was 4.3%. Two hundred thirty-two respondents completed the survey, 63.8% of whom were male, 52.6% aged 50 or younger, and 78.0% from the United States. Only 14.2% used telemedicine previously, which increased to 93.1% during COVID-19. Among all telemedicine users, usage rates were 77.9% for initial consultations, 97.2% for follow-up visits, and 35.9% for on-treatment visits. Of the respondents, 69.8% reported that <25% of patients requiring treatment experienced delays due to COVID-19. Most conducted appointments from the workplace, with 40.1% also doing so from home. Satisfaction was high at 73.8%, perceived usefulness was 76.9%, and 81.5% hope to continue using telemedicine after the pandemic. However, 82.4% had concerns with the inability to examine patients and 63.0% had concerns about poor patient access to the required technology. In addition, 49.5% had concerns regarding continued billing/reimbursement, less commonly at government centers (18.8%) compared with academic/satellite facilities (52.7%) and free-standing centers/community hospitals (50.7%, P = .039 for both comparisons). These concerns were also significantly higher among US physicians (53.2% vs 34.9%, P = .048). CONCLUSIONS: Widespread adoption of telemedicine by radiation oncologists occurred during COVID-19 with high rates of satisfaction and interest in continued use. Sustained reimbursement for telemedicine services is a significant concern, particularly in the United States and outside of government facilities.

Proton Beam Therapy for Locally Advanced Head and Neck Tumors: An Analysis of Dosimetric and Clinical Outcomes.

OBJECTIVE: Locally advanced tumors of the head and neck region often lie in close proximity to critical organs at risk (OARs). Providing effective treatment coverage to these malignancies while minimizing radiation dose to surrounding OARs is advantageous. Our aim is to compare dosimetric data of OARs from proton beam therapy (PBT) plans to volumetric modulated arc therapy (VMAT) treatment plans, and to evaluate clinical outcomes in patients treated with PBT. METHODS: We identified patients with locally advanced head and neck tumors treated with PBT at our institution from 2016 to 2019. Study endpoints included mean and maximum doses for the OAR structures for each treatment plan, overall survival, time to local-regional or distant progression, and presence of acute and late toxicities. Mean and maximum doses to OAR structures were compared between treatment modalities using a paired Wilcoxon signed-rank test. P-values <0.05 were considered significant. RESULTS: A total of 42 patients were identified. Clinical target volume coverage was >95% for both PBT and VMAT plans. PBT plans showed a significant reduction to the mean doses to all OARs, and max doses to most OARs (P<0.05). The largest reduction mean dose was seen in the contralateral cochlea and parotid glands at 71% and 75%, respectively. Median follow-up was 27 months. Overall survival at 4 years was 44.75%. Freedom from local-regional progression was 73.28% at 2 years. The majority of patients developed Common Terminology Criteria for Adverse Events (CTCAE) grade I dermatitis, mucositis, or both. CONCLUSIONS: PBT resulted in meaningful dose reductions to OARs while maintaining comparable target coverage when compared with VMAT plans. Further refinements to proton therapy may have the potential to further minimize dose to critical structures.

Thyroid-optimized and thyroid-sparing radiotherapy in oral cavity and oropharyngeal carcinoma: A dosimetric study.

BACKGROUND: Radiation-induced hypothyroidism is a common toxicity of head and neck radiation. Our re-planning study aimed to reduce thyroid dose while maintaining target coverage with IMRT. METHODS: We retrospectively identified patients with oral-cavity (n = 5) and oropharyngeal cancer (n = 5). Treatment plans were re-optimized with 45 Gy thyroid mean dose constraint, then we cropped the thyroid out of PTVs and further reduced thyroid dose. Target coverage was delivering 100% dose to ≥ 93% of PTV and 95% of dose to > 99% of PTV. RESULTS: Originally, average mean dose to thyroid was 5580 cGy. In model I, this dropped to 4325 cGy (p < 0.0001). In model II, average mean dose was reduced to 3154 cGy (p < 0.0001). For PTV low and PTV int, all had acceptable target coverage. CONCLUSION: In patients with oral-cavity and oropharyngeal cancers, mean dose could be significantly reduced using a thyroid-optimized or thyroid-sparing IMRT technique with adequate coverage.

Proton Beam Therapy in the Treatment of Periorbital Malignancies.

PURPOSE: Periorbital tumor location presents a significant challenge with 3-dimensional conformal radiation therapy or intensity modulated radiation therapy due to high tumor dose needed in the setting of close proximity to orbital structures with lower tolerance. Proton beam therapy (PBT) is felt to be an effective modality in such cases due to its sharp dose gradient. MATERIALS AND METHODS: We reviewed our institutional PBT registry and identified 17 patients with tumor epicenters within 2 cm of the eye and optic apparatus treated with passive scatter PBT with comparison volumetric arc therapy plans available. Maximum and mean doses to organs at risk of interest, including optic nerves, optic chiasm, lens, eye ball, pituitary, cochlea, lacrimal gland, and surrounding brain, were compared using the paired Wilcoxon signed rank test. Overall survival was determined using the Kaplan-Meier method. RESULTS: Median age was 67. Median follow-up was 19.7 months. Fourteen patients underwent upfront resection and received postoperative radiation and 3 received definitive radiation. One patient received elective neck radiation, 2 underwent reirradiation, and 3 had concurrent chemotherapy. There was a statistically significant reduction in mean dose to the optic nerves and chiasm, brain, pituitary gland, lacrimal glands, and cochlea as well as in the maximum dose to the optic nerves and chiasm, pituitary gland, lacrimal glands, and cochlea with PBT. The 18-month cumulative incidence of local failure was 19.1% and 1-year overall survival was 80.9%. CONCLUSION: Proton beam therapy resulted in significant dose reductions to several periorbital and optic structures compared with volumetric arc therapy. Proton beam therapy appears to be the optimal radiation modality in such cases to minimize risk of toxicity to periorbital organs at risk.

A series of typical and atypical cases of Bazex syndrome: Identifying the red herring to avoid delaying cancer treatment.

Bazex syndrome is a rare paraneoplastic dermatosis that precedes diagnosis of cancer. Awareness of this syndrome is important, as it allows early detection of underlying malignancy and may prevent misdiagnosis and delays in cancer treatment.

Reirradiation for Recurrent Scalp Angiosarcoma: Dosimetric Advantage of PBT over VMAT and EBT.

PURPOSE: Reirradiation in the scalp area can be challenging given the proximity to organs at risk (OARs), such as the eye and brain. Our aim is to evaluate the dosimetric differences of volumetric modulated arc therapy (VMAT) and electron beam therapy (EBT) compared with 3-dimensional proton beam therapy (PBT). PATIENTS AND METHODS: We evaluated a patient with recurrent angiosarcoma of the left temporal scalp after prior surgical resections and radiation therapy to 60 Gy in 30 fractions who needed reirradiation. We generated VMAT, EBT, and PBT plans using the Pinnacle Treatment Planning System (TPS). Both VMAT and EBT plans used a skin bolus, whereas no bolus was used for the proton plan. Doses to the OARs, including cochlea, eyes, lens, lacrimal glands, optic nerves, optic chiasm, pituitary gland, and underlying brain, were compared. RESULTS: The reirradiation treatment dose was 60 Gy(RBE). Target volume coverage was comparable in all plans. Compared with VMAT and EBT, the PBT plan showed reductions in mean and maximum doses to all OARs. Without the use of protons, several OARs would have exceeded dose tolerance utilizing VMAT or electrons. Dose reduction of up to 100% was achieved for central and contralateral OARs. CONCLUSION: Compared with VMAT and EBT, PBT resulted in dose reductions to all OARs, while maintaining excellent target coverage. PBT showed a significant advantage in treating superficially located skin cancers, such as angiosarcoma, without the need for a bolus. PBT can be considered in the upfront treatment and certainly in the reirradiation setting.

Emerging Opportunities for Digital PET/CT to Advance Locoregional Therapy in Head and Neck Cancer.

The purpose of this article is to present the recent imaging advancements enabled by digital photon counting positron emission tomography detector technology and discuss its potential applications in the clinical management of head and neck cancer (HNC) and nodal metastases. 18F-fluorodeoxyglucose positron-emission tomography is a clinically useful biomarker for the detection, targeted biopsy, treatment planning, and therapeutic response assessment of HNC. This article highlights the current state of 18F-fluorodeoxyglucose positron-emission tomography imaging in HNC management as well as the emerging capabilities of the recently introduced digital photon counting positron emission tomography/computed tomography platform for more effective molecular and functional HNC imaging.

Clinical outcomes and prognostic factors in cisplatin versus cetuximab chemoradiation for locally advanced p16 positive oropharyngeal carcinoma.

OBJECTIVES: Randomized trials evaluating cisplatin versus cetuximab chemoradiation (CRT) for p16+ oropharyngeal cancer (OPC) have yet to report preliminary data. Meanwhile, as a preemptive step toward morbidity reduction, the off-trial use of cetuximab in p16+ patients is increasing, even in those who could potentially tolerate cisplatin. The purpose of this study was to compare the efficacy of cisplatin versus cetuximab CRT in the treatment of p16+ OPC and to identify prognostic factors and predictors of tumor response. MATERIALS AND METHODS: Cases of p16+ OPC treated with cisplatin or cetuximab CRT at our institution from 2010 to 2014 were identified. Recursive partitioning analysis (RPA) classification was used to determine low-risk (LR-RPA) and intermediate-risk (IR-RPA) groups. Log-rank/Kaplan-Meier and Cox Regression methods were used to compare groups. RESULTS: We identified 205 patients who received cisplatin (n = 137) or cetuximab (n = 68) CRT in the definitive (n = 178) or postoperative (n = 27) setting. Median follow-up was 3 years. Cisplatin improved 3-year locoregional control (LRC) [92.7 vs 65.4%], distant metastasis-free survival (DMFS) [88.3 vs 71.2%], recurrence-free survival (RFS) [86.6 vs 50.6%], and overall survival (OS) [92.6 vs 72.2%] compared to cetuximab [all p < .001]. Concurrent cisplatin improved 3-year OS for LR-RPA (97.1 vs 80.3%, p < .001) and IR-RPA (97.1 vs 80.3%, p < .001) groupings. CONCLUSION: When treating p16+ OPC with CRT, the threshold for substitution of cisplatin with cetuximab should be maintained appropriately high in order to prolong survival times and optimize locoregional and distant tumor control. When cetuximab is used in cisplatin-ineligible patients, altered fractionation RT should be considered in an effort to improve LRC.

Correlative study of dose to thyroid and incidence of subsequent dysfunction after head and neck radiation.

BACKGROUND: Thyroid dysfunction is common after radiotherapy (RT) for patients with head and neck cancers. We attempted to discover RT dose parameters that correspond with RT-induced thyroid dysfunction. METHODS: Records of 102 patients who received RT from 2008 to 2010 were reviewed with respect to thyroid function. Abnormalities were grouped in 2 ways: (1) none, transient, or permanent; and (2) overt or subclinical. RESULTS: At median follow-up of 33.5 months, incidence of any thyroid abnormality was 39.2% (women vs men - 50% vs 35%). Permanent dysfunction was seen in 24.5% with higher incidence in women versus men (42.9% vs 17.6%; p = .0081). Permanent abnormalities most strongly correlated with D50% (p = .0275). V50Gy also correlated with thyroid dysfunction post-RT (p = .0316). Concurrent chemotherapy increased permanent dysfunction (p = .0008). CONCLUSION: Achieving D50% <50 Gy, V50 <50%, and mean dose <54.58 Gy during RT planning may decrease the incidence; whereas female sex and concurrent chemotherapy seem to increase the risk of RT-induced hypothyroidism. © 2016 Wiley Periodicals, Inc. Head Neck 39: 548-554, 2017.

High-Dose Proton Beam-Based Radiation Therapy in the Management of Extracranial Chondrosarcomas.

PURPOSE: Radiation therapy (RT) improves local tumor control in axial chondrosarcomas (CS). It is, however, often difficult to safely deliver the high doses (range, 70.2-77.4 Gy) required for achieving a high likelihood of local control, especially in the spine, using photons. This, however, can be achieved with proton beam therapy (PBT) due to its unique physical characteristics. The main goal of our study is to evaluate the outcomes of CS patients treated with passive scattered PBT. MATERIALS AND METHODS: Forty-four patients (N = 44) were identified who received PBT as part of their treatment from 1990 to 2012. A retrospective review of their medical and RT treatment records was conducted. Multivariate analyses were performed to identify patient- and tumor-related factors predicting for improved local control and overall survival. RESULTS: Median age was 45.5 years and 55% were female. Median tumor size was 13 cm. Most common anatomical location was the spine (80%). Median follow-up was 29.1 months. Median external beam RT dose was 70.2 Gy relative biological effectiveness (RBE) at 1.8 Gy (RBE) per fraction typically administered using a combination of photon RT + PBT (77%) or PBT alone (23%). Local control was 76% and 57%, and overall survival was 90% and 68% at 2 and 5 years, respectively. Toxicity was acceptable, with the most frequent being wound complications (16%). On multivariate analyses, grade III tumors were significantly associated with decreased local control (P = 0.019), while female sex (P = 0.037) and grade III tumors (P = 0.005) were associated with a poorer overall survival. CONCLUSIONS: High-dose proton-based RT in combination with surgery resulted in local tumor control in most of these high-risk CS patients. Female sex was predictive for decreased survival, while higher tumor grade (grade III) was predictive of decreased local control and survival. Proton beam therapy is an attractive treatment modality for these challenging tumors.

Sinonasal adenoid cystic carcinoma: Treatment outcomes and association with human papillomavirus.

BACKGROUND: The purpose of this study was to review long-term outcomes of sinonasal adenoid cystic carcinoma (ACC) and to clarify its association with human papillomavirus (HPV). METHODS: The medical records of 23 patients with sinonasal ACC treated with primary surgical resection between 1998 and 2013 were reviewed. Tissue specimens were available for 17 patients. The p16 testing was performed using immunohistochemistry (IHC), and HPV infection was determined using quantitative polymerase chain reaction (PCR) with primers targeting the E6/E7 region. RESULTS: Two of the 17 samples showed strong and diffuse p16 staining, whereas the remaining 15 cases showed p16-positivity isolated to the luminal cells. Only one of the p16-positive cases was positive for HPV. The 5-year local failure, disease-free survival (DFS), and overall survival (OS) were 51%, 52%, and 62%, respectively. CONCLUSION: Local failures are common with advanced sinonasal ACC, and the association of HPV with true sinonasal ACC is low.

Impact of transcutaneous neuromuscular electrical stimulation on dysphagia in patients with head and neck cancer treated with definitive chemoradiation.

BACKGROUND: The purpose of this study was to investigate the role of transcutaneous neuromuscular electrical stimulation (TNMES) therapy in maintaining swallowing function during chemoradiation for locally advanced head and neck cancer. METHODS: We retrospectively compared 43 consecutive patients with locally advanced head and neck cancer treated with TNMES (treatment group) to 55 control patients. Validated swallowing scale scores were assigned. RESULTS: All patients' swallowing scores declined post-chemoradiotherapy. A difference in mean decline in scores for the control group versus the treatment group using the Functional Oral Intake Scale (FOIS) was seen, favoring TNMES intervention (23% vs 7%; p = .015). Age, race, >10 pack-years smoking, diabetes, stage, nodal disease, accelerated fractionation, weight loss, dietary modification, no TNMES, and radiotherapy dose were all significant for poorer scores on the swallowing scales. CONCLUSION: TNMES should be considered an adjunct to dysphagia reduction and possible prevention in patients with locally advanced head and neck cancer. Further studies should be conducted to define the benefit of TNMES intervention.

Tumor volume change with stereotactic body radiotherapy (SBRT) for early-stage lung cancer: evaluating the potential for adaptive SBRT.

OBJECTIVES: To quantify gross tumor volume (GTV) change during stereotactic body radiotherapy (SBRT) and on first follow-up, as well as to evaluate for any predictive prognostic risk factors related to GTV decrease. An attempt was also made to identify the potential timing for adaptive SBRT. METHODS: Twenty-five tumors in 24 consecutive patients were treated with SBRT to total dose of 50 Gy in 5 fractions. Median age was 72.5 years. Tumor stage was T1, 68%; T2, 20%; and other, 12%. The GTVs of on the 5 cone-beam computed tomographies (CBCT1-5) obtained before each fraction and the first follow-up CT (CTPOST) were analyzed. RESULTS: Median time from diagnosis to initiation of radiotherapy was 64 days. GTV on CBCT1 was the baseline for comparison. GTV decreased by a mean of 7% on CBCT2 (P=0.148), 11% on CBCT3 (P=0.364), 19% on CBCT4 (P=0.0021), and 32% on CBCT5 (P=0.0004). Univariate analyses of GTV shrinkage was significantly associated with "time from CBCT5 to CTPOST" (P=0.027) and "T-stage" (P=0.002). In multivariate analyses, "T-stage" remained significant with T1 tumors showing greater GTV shrinkage than T2 tumors. CONCLUSIONS: Significant decrease in GTV volume based on daily CBCT was demonstrated during SBRT treatment. Adaptive SBRT has the potential to minimize integral dose to the surrounding normal tissues without compromising GTV coverage.

Negative effect of seroma on breast balloon brachytherapy dosimetry.

PURPOSE: Balloon brachytherapy is commonly used to deliver Accelerated Partial Breast Irradiation (APBI). Seroma interference is a relatively common phenomenon during APBI. The negative effect of seroma accumulation on the planning target volume evaluation (PTV_Eval) coverage is not well understood. METHODS AND MATERIALS: This is a dosimetric replanning study on 10 patients with evidence of seroma collection at time of initial computed tomographic simulation around the catheter. Total dose was 34 Gy given at 3.4 Gy twice a day over 5 treatment days. A total of 20 plans were generated, 10 plans without accounting for and 10 after subtracting the seroma. We then compared the changes seen in PTV_Eval between plans as a factor of the seroma volume. RESULTS: Median age was 62 years (51-83). Histology was invasive in 7/10 cases and in situ in 3/10. Median balloon to skin distance was 8.5 mm (3-14). Median balloon volume was 39 cc (30-104). Median seroma volume was 3.34 cc (1.13-13.71). For every 1 cc of accumulated seroma the percentage of PTV_Eval coverage by the 90% isodose line (V90) was found to decrease by 2.45% (P < .0001; confidence interval [CI], 1.87-3.03) and coverage by the 100% isodose line (V100) was decreased by 1.11% (P < .0001; CI, 0.81-1.41). Fifty percent (5/10) of previously acceptable plans with seroma not accounted for failed to meet the V90 ≥90% requirement after subtracting the seroma. CONCLUSIONS: Accumulation of seroma was associated with a considerable negative impact on PTV_Eval dosimetry with a greater impact on V90 compared with the V100. Clinicians must be careful in detecting and accounting for such accumulation in treatment plans to prevent underdosing of the at risk target breast tissue.

Current and emerging concepts in non-invasive and minimally invasive management of spine metastasis.

To provide a comprehensive review on the presentation, work-up and the management of spine metastasis with or without epidural spinal cord compression with focus on the roles of surgery and radiotherapy. Emphasis has been laid on the technological advances with recent development of stereotactic body radiotherapy (SBRT) or radiosurgery (SRS) and minimally invasive surgical approaches like kyphoplasty and vertebroplasty.

Role of nuclear medicine imaging in recognizing different causes of osteonecrosis of the jaw.

The incidence of osteonecrosis of the jaw (ONJ) among patients with cancer and metastatic bone disease being treated with bisphosphonates is as high as 10%, which dictates that an understanding of the risk factors, preventative measures, means of early diagnosis, and treatment is critical. Despite ONJ occurring in the clinical setting of intravenous bisphosphonates, there are other causes associated with higher risk of ONJ, such as multiple dental extractions. Overall, it is important for imaging health care professionals to recognize, describe, and understand ONJ to help minimize biopsies and allow proper treatment to begin as soon as possible.

Interfraction accumulation of seroma during accelerated partial breast irradiation: preliminary results of a prospective study.

PURPOSE: To quantify and characterize the process of seroma accumulation during accelerated partial breast irradiation using multicatheter balloon brachytherapy. MATERIALS AND METHODS: Twenty-two patients were treated using the Contura Multilumen brachytherapy catheter to a dose of 34Gy in 10 fractions over 5 treatment days. Serial aspirations of the vacuum port of the catheter were performed at the time of CT simulation and before each treatment. Volume and characteristics of fluid drawn were recorded. Univariate analysis was performed to evaluate various factors predictive of seroma formation. RESULTS: Median patient age was 59.5 years, body mass index was 31, and volume of surgical specimen was 62.4cm(3). Median time from breast conservation surgery to placement of Contura catheter was 18.5 days. Pericatheter seroma, typically scant with a median volume of 0.75mL, was noted in 91% of patients at CT simulation. A total of 203 aspirations were performed with a median-aspirated seroma volume of 4.05mL. There was no significant correlation between the volume of seroma and histology (invasive vs. in situ), quadrant of location, body mass index, reexcision or reoperation, days from breast conservation surgery to balloon placement, or the volume of specimen removed. Radiation treatment factors, including balloon volume, balloon to skin distance, and planning target volume evaluation, also did not correlate with aspirated seroma. CONCLUSIONS: Interfraction seroma accumulation has a variable pattern of development with no discernible predictors of occurrence. Routine pretreatment aspirations via vacuum port may potentially improve dosimetric reproducibility for a minority of patients.