RESUMO
Head and neck cancer treatment includes a multidisciplinary approach involving all specialties. Surgery and radiotherapy are equally effective in controlling small tumors. Intensity-modulated radiotherapy (IMRT) and interstitial brachytherapy (ISBT) play an important role in the treatment of head and neck cancers. Both are proved to be highly conformal techniques of radiotherapy. Our aim is to compare dosimetric aspects of ISBT alone, IMRT alone, and IMRT combined with ISBT in early stage node negative oral cavity cancer. Ten cases of histopathologically proven early stage node negative oral cavity cancer were treated with external beam therapy followed by interstitial brachytherapy boost or ISBT alone. All these patients had undergone computerized tomography (CT) planning for brachytherapy. Retrospectively, these images were utilized, and three sets of plans were done for each patient's CT image set. Group A was IMRT alone plans, groups B had combined IMRT with ISBT boost, and group C was ISBT alone plans. Dosimetric details such as target coverage, dose to critical organs, and conformity index were compared between the three sets of plans. The mean values of the doses to the critical organs with IMRT alone and IMRT with ISBT boost were brainstem 10.40 Gy and 9.20 Gy, spinal cord 19.20 Gy and 16.10 Gy, mandible 62.99 Gy and 66.50 Gy, and I/L and C/L parotids were 6.03 Gy and 5.50 Gy and 5.70 Gy and 5.10 Gy where as in ISBT alone plans mean values were brainstem 1.30 Gy, spinal cord 1.40 Gy, mandible 36.50 Gy, I/L, and C/L parotids were 1.60 Gy and 1.00 Gy. Conformity index (CI) between IMRT and ISBT plans were 0.8580 and 0.7140 respectively. With comparable CI values, doses to critical organs appear to be in favor of ISBT plans as opposed to IMRT, and this was found to be statistically significant. Brachytherapy shows a dosimetric advantage over IMRT in this setting and could be translated to a benefit in terms of toxicities, organ preservation, and cosmesis in the actual clinical scenario. However, whether this would translate to significant benefit in terms of clinical outcome needs to be still verified.
RESUMO
Squamous cell carcinoma of head and neck region account for more than 25 % of male and more than 10 % of female cancers in India (1). Head and neck cancer treatment includes a multidisciplinary approach involving all specialties. Concurrent chemo-radiation is the standard of care in most of the subsites (2). Inspite of the multi-disciplinary approach, a plateau has been reached in terms of results with 5 year survival of locally advanced disease of around 30 % (3). In order to improve outcomes, there has been considerable interest in molecular profiling of head and neck cancers 4-10. However there is still significant paucity in terms of Indian data, hence the need for the study. The objectives are to assess the HPV-p16, EGFR and p53 status, to correlate HPV-p16, EGFR and p53 status with the response rates, to correlate HPV-p16,EGFR and p53 status with other factors like age, sex, tobacco use. Twenty five consecutive cases of histopathologically proven head and neck cancers were accrued. All patients were treated with external radiation to a dose of 66Gy in 33 fractions along with concurrent weekly cisplatin chemotherapy at a dose of 40mg/sqm. HPV-p16, EGFR and p53 mutation analysis was done on paraffin embedded histopathological blocks. PCR technique used for HPV-p16, EGFR and p53 status detection. Response assessment was done based on RECIST criteria. Correlation of HPV, EGFR and p53 status on response was done. The EGFR positivity rate was 84 %, the p53 positivity rate was 76 % and the HPV p-16 positivity rate was 28 %. Out of 25 patients, 13(52%) had complete response, 7(28 %) had partial response, 3(12 %) had stable disease and 2(8 %) had progressive disease. On correlation of molecular profile with response, there was no statistical significance between EGFR status and response (p 0.5) or HPV-p16 and response (p 0.8). However, p53 positivity was approaching significance with respect to good response (p 0.07).