Krishna Sharan

DNA Double-Strand Break Analysis by γ-H2AX Foci: A Useful Method for Determining the Overreactors to Radiation-Induced Acute Reactions Among Head-and-Neck Cancer Patients

PURPOSE Interindividual variability in normal tissue toxicity during radiation therapy is a limiting factor for successful treatment. Predicting the risk of developing acute reactions before initiation of radiation therapy may have the benefit of opting for altered radiation therapy regimens to achieve minimal adverse effects with improved tumor cure. METHODS AND MATERIALS DNA double-strand break (DSB) induction and its repair kinetics in lymphocytes of head-and-neck cancer patients undergoing chemoradiation therapy was analyzed by counting γ-H2AX foci, neutral comet assay, and a modified version of neutral filter elution assay. Acute normal tissue reactions were assessed by Radiation Therapy Oncology Group criteria. RESULTS The correlation between residual DSBs and the severity of acute reactions demonstrated that residual γ-H2AX foci in head-and-neck cancer patients increased with the severity of oral mucositis and skin reaction. CONCLUSIONS Our results suggest that γ-H2AX analysis may have predictive implications for identifying the overreactors to mucositis and skin reactions among head-and-neck cancer patients prior to initiation of radiation therapy.

Influence of Double-Strand Break Repair on Radiation Therapy-Induced Acute Skin Reactions in Breast Cancer Patients

PURPOSE Curative radiation therapy (RT)-induced toxicity poses strong limitations for efficient RT and worsens the quality of life. The parameter that explains when and to what extent normal tissue toxicity in RT evolves would be of clinical relevance because of its predictive value and may provide an opportunity for personalized treatment approach. METHODS AND MATERIALS DNA double-strand breaks and repair were analyzed by microscopic γ-H2AX foci analysis in peripheral lymphocytes from 38 healthy donors and 80 breast cancer patients before RT, a 2 Gy challenge dose of x-ray exposed in vitro. RESULTS The actual damage (AD) at 0.25, 3, and 6 hours and percentage residual damage (PRD) at 3 and 6 hours were used as parameters to measure cellular radiosensitivity and correlated with RT-induced acute skin reactions in patients stratified as non-overresponders (NOR) (Radiation Therapy Oncology Group [RTOG] grade <2) and overresponders (OR) (RTOG grade ≥2). The results indicated that the basal and induced (at 0.25 and 3 hours) γ-H2AX foci numbers were nonsignificant (P>.05) between healthy control donors and the NOR and OR groups, whereas it was significant between ORs and healthy donors at 6 hours (P<.001). There was a significantly higher PRD in OR versus NOR (P<.05), OR versus healthy donors (P<.001) and NOR versus healthy donors (P<.01), supported further by the trend analysis (r=.2392; P=.0326 at 6 hours). CONCLUSIONS Our findings strongly suggest that the measurement of PRD by performing γ-H2AX foci analysis has the potential to be developed into a clinically useful predictive assay.

Polymorphisms in Radio-Responsive Genes and Its Association with Acute Toxicity among Head and Neck Cancer Patients

Cellular and molecular approaches are being explored to find a biomarker which can predict the development of radiation induced acute toxicity prior to radiation therapy. SNPs in radiation responsive genes may be considered as an approach to develop tools for finding the inherited basis of clinical radiosensitivity. The current study attempts to screen single nucleotide polymorphisms/deletions in DNA damage response, DNA repair, profibrotic cytokine as well as antioxidant response genes and its predictive potential with the normal tissue adverse reactions from 183 head and neck cancer patients undergoing platinum based chemoradiotherapy or radiotherapy alone. We analysed 22 polymorphisms in 17 genes having functional relevance to radiation response. Radiation therapy induced oral mucositis and skin erythema was considered as end point for clinical radiosensitivity. Direct correlation of heterozygous and mutant alleles with acute reactions as well as haplotype correlation revealed NBN variants to be of predictive significance in analysing oral mucositis prior to radiotherapy. In addition, genetic linkage disequilibrium existed in XRCC1 polymorphisms for >grade 2 oral mucositis and skin reaction indicating the complex inheritance pattern. The current study indicates an association for polymorphism in NBN with normal tissue radiosensitivity and further warrants the replication of such studies in a large set of samples.

Statistical Modelling and Forecasting of Cervix Cancer Cases in Radiation Oncology Treatment: A Hospital Based Study from Western Nepal

BACKGROUND To estimate the numbers and trends in cervix cancer cases visiting the Radiotherapy Department at Manipal Teaching Hospital, Pokhara, Nepal, statistical modelling from retrospective data was applied. MATERIALS AND METHODS A retrospective study was carried out on data for a total of 159 patients treated for cervix cancer at Manipal Teaching Hospital, Pokhara, Nepal, between 28th September 2000 and 31st December 2008. Theoretical statistics were used for statistical modelling and forecasting. RESULTS Using curve fitting method, Linear, Logarithmic, Inverse, Quadratic, Cubic, Compound, Power and Exponential growth models were validated. Including the constant term, none of the models fit the data well. Excluding the constant term, the cubic model demonstrated the best fit, with R2=0.871 (p=0.004). In 2008, the observed and estimated numbers of cases were same (12). According to our model, 273 patients with cervical cancer are expected to visit the hospital in 2015. CONCLUSIONS Our data predict a significant increase in cervical cancer cases in this region in the near future. This observation suggests the need for more focus and resource allocation on cervical cancer screening and treatment.

Treatment outcomes after intraluminal brachytherapy following definitive chemoradiotherapy in patients with esophageal cancer

AIMS AND OBJECTIVES To report the results of treatment with intraluminal brachytherapy (ILRT) after concurrent chemoradiotherapy for esophageal carcinoma with respect to disease free survival (DFS), dysphagia free interval (DFI), and complications of treatment. MATERIALS AND METHODS The study retrospectively analyzed the records of 26 eligible patients with nonmetastatic carcinoma of the esophagus treated with definitive chemoradiotherapy followed by ILRT between 2008 and 2011. The DFS and DFI were estimated and factors likely to influence them were analyzed. RESULTS Nineteen (73%) patients were males. The mean age at presentation was 60 years (range: 47-90 years). All the patients had squamous cell carcinomas. Following treatment, the median DFS was 12.7 months (range: 0-27 months). Sixteen patients (61.5%) had local control of their disease, while one had residual disease at completion of treatment. Other than three patients who were not evaluated for recurrent dysphagia, six (23.1%) had proven local recurrence on follow-up. The estimated mean DFI was 13.8 months (range: 0-27 months). One patient died of tracheoesophageal fistula following treatment. On statistical analysis, only the location of tumor was prognostically significant, with lower third tumors performing worse. Other probable predictors of poor outcome included large volume (> 40 cc), tumor length (> 6 cm), and eccentric location. CONCLUSION ILRT boost following concurrent chemoradiotherapy is well tolerated and potentially improves outcomes. It might be beneficial in selected patients with esophageal carcinoma. Further studies are required to identify its role in definitive treatment.

Chemoradiation related acute morbidity in carcinoma cervix and correlation with hematologic toxicity: a South Indian prospective study.

PURPOSE To assess chemoradiation related acute morbidity in women with carcinoma cervix and to find and correlation between hematologic toxicity and organ system specific damage. MATERIALS AND METHODS A prospective study was carried out between August 2012 and July 2013 enrolling 79 women with cancer cervix receiving chemo-radiotherapy. Weekly assessment of acute morbidity was done using the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI CTCAE) version 4 and the toxicities were graded. RESULTS Anemia [77 (97.5%)], vomiting [75 (94.8%)] and diarrhea [72 (91.1%)], leukopenia [11 (13.9%)], cystitis [28 (35.4%], dermatitis [19 (24.1%)] and fatigue [29 (36.71%)] were the acute toxicities noted. The toxicities were most severe in 3rd and 5th week. All women could complete radiotherapy except two due to causes unrelated to radiation morbidity; seven (8.86%) had to discontinue chemotherapy due to leukopenia and intractable diarrhea. Though there was no correlation between anemia and other toxicities, it was found that all with leukopenia had diarrhea. CONCLUSIONS Chemoradiation for cancer cervix is on the whole well tolerated. Leukopenia and severe diarrhea were the acute toxicities that compelled discontinuation of chemotherapy in two women. Though anemia had no correlation with gastrointestinal toxicity, all of those with leukopenia had diarrhea.

A Study on Dosimetric Outcomes and Acute Toxicity of Post Mastectomy Adjuvant Hypofractionated Radiotherapy for Breast Cancer.

INTRODUCTION Hypofractionated External Beam Radiotherapy (HFRT) is a relatively new adjuvant Radiotherapy (RT) schedule for breast cancers following breast conservation surgery and less commonly, following mastectomy. Here we report our experience on normal tissue exposure and acute toxicity of HFRT after mastectomy. AIM To assess the dosimetric outcomes and acute toxicity profile of adjuvant HFRT following mastectomy for breast cancer. MATERIALS AND MATERIALS This prospective observational study considered consecutive patients planned for adjuvant HFRT (42.5 Gy in 16 sessions delivered over 3 weeks) to the chest wall with/without regional nodes between October 2014 and June 2015. The dosimetric parameters including dose homogeneity to the target volume and exposure to heart and lung were analyzed. Acute haematological and dermatological toxicity was recorded until upto three months after completion of RT. RESULTS Among the 56 patients treated with HFRT, the mean age was 49 years (range: 28-69 years). Pathologically positive nodes and ≥pT3 primary was observed in 44 (78.6%) and 12 (21.4%) patients, respectively. Majority (87.5%) received prior adjunct chemotherapy. RT to the supraclavicular fossa was delivered for 39 (69.6%) patients. The mean V90 and V95 to the Planning Target Volume (PTV) were 95% (± 3.3%) and 93% (± 4%), respectively. The maximum dose received was on average 47.7 Gy (112%; range: 46.2-48.5 Gy). The mean lung dose was 10.2 Gy (± 3.5 Gy) and V20 was 20.9% (± 6%). The mean V25 to heart was 6.6% (± 4.8%) for left sided and 0% for right sided tumours (p=0.001). Acute skin toxicity peaked at completion of RT and was tolerable (grade 0, I, II and III reactions were 75%, 16% and 1.8%, respectively). No patient had ≥ grade III haematological toxicity, and treatment was not interrupted for any patient. CONCLUSION Adjuvant HFRT could be planned while meeting the dose constraints to normal tissues in all patients and was well tolerated, with mild to moderate acute adverse effects that did not warrant any therapeutic intervention or treatment interruption.