Progression of gingival squamous cell carcinoma from early to late stage after invasive dental procedure.

Early presentation of gingival squamous cell carcinoma (GSCC) is at times misdiagnosed as a benign inflammatory or reactive oral condition. Some misdiagnosed patients undergo unnecessary, invasive dental procedures, resulting in delayed cancer diagnosis and an increased risk of accelerated disease progression due to disruption of the periosteum and cortical bone. The records of 58 patients with biopsy-proven GSCC were retrospectively reviewed. The sample included 32 patients who underwent an invasive dental procedure (IDP) prior to cancer diagnosis and 26 patients who did not undergo an IDP (non-case group). Patients from both groups initially presented with similar symptoms. The median duration of symptoms at initial clinical presentation was 6 months for the IDP group and 2 months for the non-case group. In IDP patients, symptoms worsened after the IDP was rendered, with 37.5% presenting with a severe-grade symptom. In both groups, the majority of lesions were found on the posterior mandible and had a histologic grading of moderately differentiated GSCC. The odds of the IDP group having late-stage disease were 2.94 times greater than the odds for the control group. Stage T3/T4 malignancy was diagnosed in 77.4% of the IDP patients versus 53.8% of non-case patients. Disease-specific mortality was comparable; however, surgical treatment was significantly more extensive in the IDP group than in the non-case group. The disruption of alveolar periosteum in undiagnosed oral cancer patients results in significant delay in diagnosis, necessitating more complicated treatment regimens because of local tumor progression.

Photodynamic therapy with 3-(1'-hexyloxyethyl) pyropheophorbide-a for early-stage cancer of the larynx: Phase Ib study.

BACKGROUND: The purpose of this study was for us to report results regarding the safety of 3-(1'-hexyloxyethyl) pyropheophorbide-a (HPPH) mediated photodynamic therapy (PDT) in early laryngeal disease, and offer preliminary information on treatment responses. METHODS: A single-institution, phase Ib, open label, noncomparative study of HPPH-PDT in patients with high-risk dysplasia, carcinoma in situ, and T1 squamous cell carcinoma (SCC) of the larynx. The primary outcomes were safety and maximum tolerated dose (MTD), and the secondary outcome was response. RESULTS: Twenty-nine patients and 30 lesions were treated. The most common adverse event (AE) was transient hoarseness of voice. Severe edema, requiring tracheostomy, was the most serious AE, which occurred in 2 patients within several hours of therapy. The MTD was 100 J/cm(2) . Patients with T1 SCC seemed to have good complete response rate (82%) to HPPH-PDT at MTD. CONCLUSION: HPPH-PDT can be safely used to treat early-stage laryngeal cancer, with potential efficacy. © 2015 The Authors Head & Neck Published by Wiley Periodicals, Inc. Head Neck 38: E377-E383, 2016.

Image-guided Interstitial Photodynamic Therapy for Squamous Cell Carcinomas: Preclinical investigation.

OBJECTIVE: Photodynamic therapy (PDT) is a clinically approved minimally invasive treatment for cancer. In this preclinical study, using an imaging-guided approach, we examined the potential utility of PDT in the management of bulky squamous cell carcinomas (SCCs). METHODS: To mimic bulky oropharyngeal cancers seen in the clinical setting, intramuscular SCCs were established in six-to-eight week old female C3H mice. Animals were injected with the photosensitizer, 2-[hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH; 0.4 µmol/kg, i.v.) and tumors were illuminated 24 hours post injection with 665 nm light. PDT as a single treatment modality was administered by surface illumination or by interstitial placement of fibers (iPDT). Magnetic resonance imaging was used to guide treatment and assess tumor response to PDT along with correlative histopathologic assessment. RESULTS: Interstitial HPPH-PDT resulted in a marked change on T2 maps 24 hours post treatment compared to untreated controls or transcutaneous illumination. Corresponding apparent diffusion coefficient maps also showed hyperintense areas in tumors following iPDT suggestive of effective photodynamic cell kill. Histologic sections (H&E) confirmed presence of extensive tumor necrosis following iPDT. CONCLUSIONS: These results highlight the potential utility of PDT in the treatment of bulky oropharyngeal cancers. The findings of our study also demonstrate the utility of MRI as a non-invasive tool for mapping of early tissue response to PDT.

Survival differences between organ preservation surgery and definitive radiotherapy in early supraglottic squamous cell carcinoma.

OBJECTIVE: Single-modality treatment, either with organ preservation surgery (OPS) or definitive radiation (RT), is the treatment of choice for patients with early supraglottic squamous cell carcinoma (SGC). However, studies comparing the effectiveness of these 2 techniques are lacking. This study compares the survival outcomes in early SGC patients treated with OPS versus RT. STUDY DESIGN: Secondary data analysis. SETTING: Surveillance, Epidemiology and End Results database. SUBJECTS AND METHODS: This study included adult patients with early-stage (T1N0, T2N0) SGC undergoing single-modality treatment with either OPS (with or without neck dissection [ND]) or RT between 1988 and 2008. Survival analysis was used to compare the overall survival (OS) and disease-specific survival (DSS) between patients treated with OPS+ND, OPS alone, and RT. RESULTS: A total of 2631 T1/T2 N0 SGC patients were identified, of whom 167 (6%) were treated with OPS+ND, 186 (7%) with OPS only, and 2278 patients (87%) with definitive RT only. In stage I (T1N0) SGC patients, a significantly better 5-year DSS was noted for both OPS+ND (81% vs 68%, hazard ratio [HR] = 0.61, P = .03) and OPS only (82% vs 68%, HR = 0.70, P = .05) when compared with definitive RT. For stage II (T2N0) patients, only OPS+ND resulted in a significantly better 5-year DSS (86% vs 60%, HR = 0.31, P < .001) when compared with patients treated with RT. CONCLUSIONS: Patients with early SGC who underwent OPS+ND had better OS and DSS than patients undergoing RT alone. OPS+ND may be considered a viable and preferred treatment option in these patients.

Survival rates and prognostic factors for infiltrating salivary duct carcinoma: Analysis of 228 cases from the Surveillance, Epidemiology, and End Results database.

BACKGROUND: The survival rates and prognostic factors for salivary duct carcinoma (SDC) are not clear. METHODS: Survival estimates and prognostic factors were evaluated for 228 patients with SDC identified from the Surveillance, Epidemiology, and End Results (SEER) database. RESULTS: Median overall survival (OS) duration for patients with SDC was 79 months and 5-year disease-specific survival (DSS) rate was 64%. Among patients with SDC with lymph node involvement, larger primary tumor size (>3 cm) was associated with twice the risk of death (p < .03). Factors predictive of improved DSS were age (p = .01), tumor size (p = .006), tumor grade (p = .02), and lymph node involvement (p < .001). Adjuvant radiotherapy did not improve survival when compared to surgery alone for early-stage (I-II) disease (p = .28). CONCLUSION: Younger patients with SDC (<50 years) showed a better prognosis. Primary tumor size and lymph node involvement were independent and additive risk factors for poor prognosis. The role of adjuvant radiotherapy in the treatment of SDC needs to be explored further.

Photodynamic therapy with 3-(1'-hexyloxyethyl) pyropheophorbide a for cancer of the oral cavity.

PURPOSE: The primary objective was to evaluate safety of 3-(1'-hexyloxyethyl)pyropheophorbide-a (HPPH) photodynamic therapy (HPPH-PDT) for dysplasia and early squamous cell carcinoma of the head and neck (HNSCC). Secondary objectives were the assessment of treatment response and reporters for an effective PDT reaction. EXPERIMENTAL DESIGN: Patients with histologically proven oral dysplasia, carcinoma in situ, or early-stage HNSCC were enrolled in two sequentially conducted dose escalation studies with an expanded cohort at the highest dose level. These studies used an HPPH dose of 4 mg/m(2) and light doses from 50 to 140 J/cm(2). Pathologic tumor responses were assessed at 3 months. Clinical follow up range was 5 to 40 months. PDT induced cross-linking of STAT3 were assessed as potential indicators of PDT effective reaction. RESULTS: Forty patients received HPPH-PDT. Common adverse events were pain and treatment site edema. Biopsy proven complete response rates were 46% for dysplasia and carcinoma in situ and 82% for squamous cell carcinomas (SCC) lesions at 140 J/cm(2). The responses in the carcinoma in situ/dysplasia cohort are not durable. The PDT-induced STAT3 cross-links is significantly higher (P = 0.0033) in SCC than in carcinoma in situ/dysplasia for all light doses. CONCLUSION: HPPH-PDT is safe for the treatment of carcinoma in situ/dysplasia and early-stage cancer of the oral cavity. Early-stage oral HNSCC seems to respond better to HPPH-PDT in comparison with premalignant lesions. The degree of STAT3 cross-linking is a significant reporter to evaluate HPPH-PDT-mediated photoreaction.

Pectoralis major myocutaneous flap for reconstruction of circumferential pharyngeal defects.

BACKGROUND: A 270-degree partially tubed pectoralis major myocutaneous flap (PMMF) is an excellent option for total circumferential pharyngoesophageal defects in patients who are not candidates for more complex reconstructions. METHODS: Patients undergoing circumferential pharyngoesophageal reconstruction with partially tubed PMMF were reviewed. End points were stricture, fistula, resumption of oral intake, perioperative death, and recurrence. RESULTS: Eleven patients underwent 270-degree PMMF for reconstruction: 6 (55%) were men and 5 (45%) were women (mean, 62 years; range, 42-78 years). Three patients (27%) developed fistulas and 2 (18%) developed stenosis. Ten patients (91%) were able to resume adequate nutrition via oral intake. There were no perioperative deaths. CONCLUSIONS: Patients with severe comorbidities, metastatic disease, a lack of donor vessels, or a potentially hostile abdomen may not be ideal candidates for free tissue transfer. For these patients, partially tubed PMMF using the prevertebral fascia provides a reliable alternative for reconstruction with excellent functional results.

Vascular priming enhances chemotherapeutic efficacy against head and neck cancer.

PURPOSE: The need to improve chemotherapeutic efficacy against head and neck squamous cell carcinomas (HNSCC) is well recognized. In this study, we investigated the potential of targeting the established tumor vasculature in combination with chemotherapy in head and neck cancer. METHODS: Experimental studies were carried out in multiple human HNSCC xenograft models to examine the activity of the vascular disrupting agent (VDA) 5,6-dimethylxanthenone-4-acetic acid (DMXAA) in combination with chemotherapy. Multimodality imaging (magnetic resonance imaging, bioluminescence) in conjunction with drug delivery assessment (fluorescence microscopy), histopathology and microarray analysis was performed to characterize tumor response to therapy. Long-term treatment outcome was assessed using clinically-relevant end points of efficacy. RESULTS: Pretreatment of tumors with VDA prior to administration of chemotherapy increased intratumoral drug delivery and treatment efficacy. Enhancement of therapeutic efficacy was dependent on the dose and duration of VDA treatment but was independent of the chemotherapeutic agent evaluated. Combination treatment resulted in increased tumor cell kill and improvement in progression-free survival and overall survival in both ectopic and orthotopic HNSCC models. CONCLUSION: Our results show that preconditioning of the tumor microenvironment with an antivascular agent primes the tumor vasculature and results in enhancement of chemotherapeutic delivery and efficacy in vivo. Further investigation into the activity of antivascular agents in combination with chemotherapy against HNSCC is warranted.

Sentinel node biopsy in lieu of neck dissection for staging oral cancer.

IMPORTANCE: Neck dissection is the standard staging procedure to ascertain the pathologic status of cervical lymph nodes in patients with oral cavity squamous cell carcinoma (OSCC), but it results in multiple morbidities. OBJECTIVE: To examine outcomes of patients with OSCC who underwent sentinel node biopsy (SNB) as the sole neck staging procedure. DESIGN: Retrospective review of patients who underwent SNB during the period 2005 through 2011. SETTING: National Cancer Institute­designated comprehensive cancer center. PARTICIPANTS: Thirty-eight patients with clinically T1 or T2N0 OSCC. INTERVENTIONS: Preoperative lymphoscintigraphy with intraoperative gamma probe localization was used. Sentinel lymph nodes were serially sectioned, formalin fixed, and examined at 3 levels. All patients with positive SNB results underwent neck dissection, and the patients with negative SNB results were observed clinically. MAIN OUTCOMES AND MEASURES: Sensitivity and predictive value of SNB, recurrence rates, and disease-specific survival rates. RESULTS: There were 18 T1 and 20 T2 tumors. Five patients had positive SNB results, of whom 3 had additional positive nodes on subsequent neck dissection. Two of 33 patients with negative SNB results developed a regional recurrence. The sensitivity and negative predictive value for staging the neck with SNB alone were 71% (5 of 7) and 94% (31 of 33), respectively. Mean follow-up was 31 months. The mean disease-free survival duration for patients with positive and negative SNB results was 30 and 65 months, respectively (P = .08). The disease-specific survival rate for patients with positive and negative SNB results was 80% and 91%, respectively. There was no significant difference in disease-specific survival between patients with true-negative and false-negative SNB results (34 vs 44 months; P = .38). CONCLUSIONS AND RELEVANCE: The majority of patients with positive results on SNB had additional positive nodes on neck dissection. A low rate of isolated neck recurrence was found in patients with negative results on SNB. Individuals with negative results on SNB exhibited better overall and disease-specific survival than those with positive results.

Adjuvant intraoperative photodynamic therapy in head and neck cancer.

IMPORTANCE: There is an immediate need to develop local intraoperative adjuvant treatment strategies to improve outcomes in patients with cancer who undergo head and neck surgery. OBJECTIVES: To determine the safety of photodynamic therapy with 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH) in combination with surgery in patients with head and neck squamous cell carcinoma. DESIGN, SETTING, AND PARTICIPANTS: Nonrandomized, single-arm, single-site, phase 1 study at a comprehensive cancer center among 16 adult patients (median age, 65 years) with biopsy-proved primary or recurrent resectable head and neck squamous cell carcinoma. INTERVENTIONS: Intravenous injection of HPPH (4.0 mg/m2), followed by activation with 665-nm laser light in the surgical bed immediately after tumor resection. MAIN OUTCOMES AND MEASURES: Adverse events and highest laser light dose. RESULTS: Fifteen patients received the full course of treatment, and 1 patient received HPPH without intraoperative laser light because of an unrelated myocardial infarction. Disease sites included larynx (7 patients), oral cavity (6 patients), skin (1 patient), ear canal (1 patient), and oropharynx (1 patient, who received HPPH only). The most frequent adverse events related to photodynamic therapy were mild to moderate edema (9 patients) and pain (3 patients). One patient developed a grade 3 fistula after salvage laryngectomy, and another patient developed a grade 3 wound infection and mandibular fracture. Phototoxicity reactions included 1 moderate photophobia and 2 mild to moderate skin burns (2 due to operating room spotlights and 1 due to the pulse oximeter). The highest laser light dose was 75 J/cm2. CONCLUSIONS AND RELEVANCE: The adjuvant use of HPPH-photodynamic therapy and surgery for head and neck squamous cell carcinoma seems safe and deserves further study. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00470496.

Pretreatment weight status and weight loss among head and neck cancer patients receiving definitive concurrent chemoradiation therapy: implications for nutrition integrated treatment pathways.

PURPOSE: The purpose was to examine the effect of pretreatment weight status on loco-regional progression for patients with squamous cell carcinoma of the head and neck (SCCHN) after receiving definitive concurrent chemoradiation therapy (CCRT). METHODS: In an expanded cohort of 140 patients, we retrospectively reviewed weight status and loco-regional progression of SCCHN patients treated with CCRT between 2004 and 2010. RESULTS: Pretreatment ideal body weight percentage (IBW%) was statistically significantly different for patients with disease progression than for those without progression (p = 0.02) but was not an independent predictor of progression. Median pretreatment IBW% was 118 (72-193) for the progression-free group and was 101.5 (73-163) for the group with progression. Both groups suffered clinically severe weight loss of approximately 9 % from baseline to end treatment. CONCLUSIONS: Pretreatment weight status, a very crude indicator of nutrition status, may have prognostic value in patients with SCCHN undergoing definitive CCRT. Inadequate nutritional status in these patients has been associated with poor clinical outcomes and decreased quality of life. Based on this report and others, the best next steps include routine validated malnutrition screening and the testing of evidence-based nutrition care protocols with the goals of minimizing weight loss and improvement of quality of life.

Cranial base repair with combined vascularized nasal septal flap and autologous tissue graft following expanded endonasal endoscopic neurosurgery.

BACKGROUND: The expanded endonasal endoscopic approach provides excellent visualization and access to midline skull base lesions, albeit with a relatively high risk of postoperative cerebrospinal fluid (CSF) leakage. We present our experience with the expanded endonasal endoscopic approach to the skull base in an institution where, previously, a traditional transsphenoidal approach with a surgical microscope had been used. PATIENTS: We performed a retrospective review to identify patients who underwent expanded endonasal endoscopic surgery and analyzed demographic, pathological, and operative data with particular attention to repair of the skull base defects in 55 procedures performed on 49 patients. We compared the outcomes of 10 primary operations in which we repaired skull base defects using only autologous or allogeneic tissue grafts and 39 primary operations in which we used a vascularized mucoperichondrial nasal septal flap with or without a layered autologous tissue graft. RESULTS: Primary expanded endonasal endoscopic procedures were performed in 49 patients with sellar pathology (33 pituitary adenomas, 4 Rathke's cleft cysts, 1 pituicytoma, 1 pituitary metastasis) and non-sellar pathology (3 meningiomas, 3 clival chordomas, 1 clival mucocele, 1 craniopharyngioma, and 2 esthesioneuroblastomas). Postoperative CSF leakage occurred following 5 of the 49 primary operations (10.2%). This occurred in 2 of 10 primary operations (20.0%) in which the skull base defect was repaired using only autologous and/or allogeneic tissue grafts, necessitating a total of 3 operative CSF leak repairs in those 2 patients. The remaining 3 postoperative CSF leaks occurred in the 39 primary operations (7.7%) in which skull base repair was performed using a mucoperichondrial nasal septal flap, necessitating operative repair in 2 of those patients. CONCLUSION: The repair of skull base defects created during expanded endonasal endoscopic surgery is improved by use of a mucoperichondrial nasal septal flap combined with a layered autologous tissue graft. When CSF leakage occurs despite nasal septal flap closure, the site of the leakage may be easier to localize and repair.

Quantification of the effect of treatment duration on local-regional failure after definitive concurrent chemotherapy and intensity-modulated radiation therapy for squamous cell carcinoma of the head and neck.

BACKGROUND: The purpose of this study was to quantify the effect of treatment duration on locoregional progression after definitive concurrent chemoradiation (CCRT) for squamous cell carcinoma of the head and neck (SCCHN). METHODS: We conducted a retrospective chart review of patients treated between 2004 and 2010. After a prior analysis, measures were taken to limit therapy beyond 7 weeks. Comparison of outcomes were made between cohorts 1 (2004-2007, n = 78) and 2 (2007-2010, n = 62). RESULTS: Median therapy duration was statistically significantly different between cohorts as follows: 51 days, cohort 1 and 46 days, cohort 2 (p < .01). Locoregional progression in cohorts 1 and 2 was 19% and 5% (p = .01), respectively. On multivariate analysis, patients with prolonged treatment (≥57 days) had an 8-fold increase in risk of locoregional progression compared to patients who completed on time (p < .01). CONCLUSION: Treatment duration was a significant predictor of locoregional progression in patients with SCCHN who received definitive CCRT.

Interlesion differences in the local photodynamic therapy response of oral cavity lesions assessed by diffuse optical spectroscopies.

Photodynamic therapy (PDT) efficacy depends on the local dose deposited in the lesion as well as oxygen availability in the lesion. We report significant interlesion differences between two patients with oral lesions treated with the same drug dose and similar light dose of 2-1[hexyloxyethyl]-2-devinylpyropheophorbide-a (HPPH)-mediated photodynamic therapy (PDT). Pre-PDT and PDT-induced changes in hemodynamic parameters and HPPH photosensitizer content, quantified by diffuse optical methods, demonstrated substantial differences between the two lesions. The differences in PDT action determined by the oxidative cross-linking of signal transducer and activator of transcription 3 (STAT3), a molecular measure of accumulated local PDT photoreaction, also showed >100-fold difference between the lesions, greatly exceeding what would be expected from the slight difference in light dose. Our results suggest diffuse optical spectroscopies can provide in vivo metrics that are indicative of local PDT dose in oral lesions.

Local inflammation and human papillomavirus status of head and neck cancers.

OBJECTIVE: To determine whether periodontitis is associated with human papillomavirus (HPV) status of head and neck squamous cell carcinoma (HNSCC). DESIGN AND SETTING: Hospital-based case-control study in a comprehensive cancer center. PATIENTS: Evaluation included all patients diagnosed with incident primary squamous cell carcinoma of the oral cavity, oropharynx, and larynx between 1999 and 2007 for whom tissue samples and dental records were available (N = 124). Patients younger than 21 years and those with a history of cancer were excluded. Periodontitis history was assessed by alveolar bone loss in millimeters from panoramic radiographs by one examiner blinded to cancer status. MAIN OUTCOME MEASURE: The presence of HPV-16 DNA in paraffin-embedded tumor samples was identified by polymerase chain reaction. RESULTS: The prevalence of HPV-positive HNSCC was 50 of 124 patients (40.3%). A higher proportion of oropharyngeal cancers were HPV-positive (32 of 49 [65.3%]) compared with oral cavity (9 of 31 [29.0%]) and laryngeal (9 of 44 [20.5%]) cancers. Each millimeter of alveolar bone loss was associated with 2.6 times increased odds (odds ratio [OR], 2.61; 95% CI, 1.58-4.30) of HPV-positive tumor status after adjustment for age at diagnosis, sex, and smoking status. The strength of the association was greater among patients with oropharyngeal SCC (OR, 11.70; 95% CI, 2.09-65.53) compared with those with oral cavity SCC (OR, 2.32; 95% CI, 0.65-8.27) and laryngeal SCC (OR, 3.89; 95% CI, 0.95-15.99). CONCLUSIONS: A history of chronic inflammatory disease in the oral cavity may be associated with tumor HPV status in patients with HNSCC. This association seems to be stronger among patients with oropharyngeal cancer compared with those who have oral cavity or laryngeal SCC.

Pretreatment nutritional status and locoregional failure of patients with head and neck cancer undergoing definitive concurrent chemoradiation therapy.

BACKGROUND: This study was carried out to determine if markers of nutritional status predict for locoregional failure following intensity-modulated radiation therapy (IMRT) with concurrent chemoradiotherapy (CCRT) for squamous cell carcinoma of the head and neck (SCCHN). METHODS: We performed a retrospective chart review of 78 patients with SCCHN who received definitive CCRT. We compared patient factors, tumor characteristics, and nutritional status indicators between patients with and without locoregional failure. RESULTS: Fifteen of 78 patients (19%) experienced locoregional failure. Median follow-up for live patients was 38 months. On univariate analysis, pretreatment percentage of ideal body weight (%IBW) (p < .01), pretreatment hemoglobin (p = .04), and treatment duration (p < .01) were significant predictors of failure. On multivariate analysis, pretreatment %IBW (p = .04) and treatment time (p < .01) remained statistically significant. CONCLUSIONS: Although treatment time is an accepted risk factor for failure, differences in outcome for patients with head and neck cancer undergoing definitive CCRT based on pretreatment %IBW should be examined further.

In vitro cellular uptake and dimerization of signal transducer and activator of transcription-3 (STAT3) identify the photosensitizing and imaging-potential of isomeric photosensitizers derived from chlorophyll-a and bacteriochlorophyll-a.

Among the photosensitizers investigated, both ring-D and ring-B reduced chlorins containing the m-iodobenzyloxyethyl group at position-3 and a carboxylic acid functionality at position-17(2) showed the highest uptake by tumor cells and light-dependent photoreaction that correlated with maximal tumor-imaging [positron emission tomography (PET) and fluorescence] and long-term photodynamic therapy (PDT) efficacy in BALB/c mice bearing Colon26 tumors. However, among the ring-D reduced compounds, the isomer containing the 1'-m-iobenzyloxyethyl group at position-3 was more effective than the corresponding 8-(1'-m-iodobenzyloxyethyl) derivative. All photosensitizers showed maximum uptake by tumor tissue 24 h after injection, and the tumors exposed with light at low fluence and fluence rates (128 J/cm(2), 14 mW/cm(2)) produced significantly enhanced tumor eradication than those exposed at higher fluence and fluence rate (135 J/cm(2), 75 mW/cm(2)). Interestingly, dose-dependent cellular uptake of the compounds and light-dependent STAT3 dimerization have emerged as sensitive rapid indicators for PDT efficacy in vitro and in vivo and could be used as in vitro/in vivo biomarkers for evaluating and optimizing the in vivo treatment parameters of the existing and new PDT candidates.