Myths, facts and scope of spinal cord tolerance dose revision in Intensity modulated SIB treatment of locally advanced head and neck cancer: A dosimetrical and radiobiological demonstration.

PURPOSE: To explore the possibility of revising the spinal cord tolerance dose in Simultaneously Integrated Boost (SIB) intensity modulated treatment plan of locally advanced head and neck (H&N) cancer and assessment of achieved planning gain due to the revision. In SIB regimen, the Organ at Risk (OARs) tolerance dose is equally distributed throughout the treatment. Clinicians have usually considered the spinal cord tolerance to be the same as in conventional technique. However, in SIB fractionation regimen with intensity modulation treatment, the spinal cord may receive a physical dose of 45Gy, with much lesser dose per fraction than 2Gy per fraction. So when the dose of spinal cord is distributed throughout the treatment, the tolerance dose limit of physical dose can be considered higher than the usual conventional dose limits. In this study, an attempt has been made to explore the possibilities of dose escalation and treatment planning benefits while exploiting this "Window of Opportunity (WoO)" of increase in spinal cord and Planning Risk Volume (PRV) spinal cord tolerance dose. MATERIAL AND METHODS: A total of 12 patients CT data set along with approved structure set of H&N cancer used for treatment planning in. Three independent SIB VMAT plans named as SPC, SPR and SPDE were generated for the 12 patients. First plan (SPC) was generated by considering standard spinal cord tissue constraint of maximum dose of 45Gy and PRV spinal cord maximum dose 50Gy as per QUANTEC summary and second plan (SPR) was generated considering spinal cord tissue constraint of maximum dose 52.50Gy and PRV spinal cord maximum dose 56.35Gy while optimization and dose calculation. The objectives for rest of the Organ at Risk (OAR) were kept same in both the plans during optimization and dose calculation. The SPC plan was copied for creation of third plan (SPDE) in which dose was escalated by increasing dose per fraction for target volumes such that dose to spinal cord reached a maximum dose of 52.50Gy and PRV spinal cord maximum dose of 56.35Gy. In this plan there have been changes to only dose per fraction, however dose optimization and dose calculation have not been performed. Radiobiological parameters TCP and NTCP were also calculated by using indigenously developed software. RESULTS: Considering the increase of spinal cord tolerance dose as "window of opportunity", a sufficient escalation in physical dose, Biological Effective Dose (BED) and Tumor Control Probability (TCP) was observed for all target volumes with acceptable level of NTCP values. CONCLUSION: Sufficient dose escalation and increased in TCP for target volumes or effective planning benefits can be achieved by revising the spinal cord tolerance dose in intensity modulated SIB treatment of locally advanced H&N cancers.

Distribution of HPV Genotypes and Involvement of Risk Factors in Cervical Lesions and Invasive Cervical Cancer: A Study in an Indian Population.

Human papilloma virus (HPV) is considered as the main sexually transmitted etiological agent for the cause and progression of preneoplastic cervical lesions to cervical cancer. This study is discussing the prevalence of HPV and its genotypes in cervical lesions and invasive cervical cancer tissues and their association with various risk factors in women from Varanasi and its adjoining areas in India. A total of 122 cervical biopsy samples were collected from SS Hospital and Indian Railways Cancer Institute and Research Centre, Varanasi and were screened for HPV infection by PCR using primers from L1 consensus region of the viral genome. HPV positive samples were genotyped by type-specific PCR and sequencing. The association of different risk factors with HPV infection in various grades of cervical lesion was evaluated by chi-square test. A total of 10 different HPV genotypes were observed in women with cervicitis, CIN, invasive squamous cell cervical carcinoma and adenocarcinoma. Increased frequency of HPV infection with increasing lesion grade (p=0.002) was observed. HPV16 being the predominant type was found significantly associated with severity of the disease (p=0.03). Various socio- demographic factors other than HPV including high parity (p<0.0001), rural residential area (p<0.0001), elder age (p<0.0001), low socio-economic status (p<0.0001) and women in postmenopausal group (p<0.0001) were also observed to be associated with cervical cancer.These findings show HPV as a direct cause of cervical cancer suggesting urgent need of screening programs and HPV vaccination in women with low socio-economic status and those residing in rural areas.

Primary oesophageal carcinoma in teens.

Seven teenaged patients with primary oesophageal carcinoma, treated at our hospital in the last 6 years are presented and their management discussed. Five patients had localised disease. Three of them underwent total oesophagectomy, one was given radical radiotherapy, and one was lost to follow-up. Two patients had metastatic disease at presentation. The primary oesophageal carcinoma in this age group may not be so rare as reported in the literature and must be considered in the differential diagnosis of dysphagia. Like their older counterparts, the outcome depends on the stage of the disease and is not influenced by age per se.

Carcinoma oesophagus in a 14 year old child: report of a case and review of literature.

A 14 year old boy with well differentiated squamous cell carcinoma of the upper oesophagus is being presented because of its rarity. The patient presented with dysphagia for 8 months. Barium swallow and endoscopy revealed a narrowing in the upper oesophagus with a proximal dilatation diverticulum. No definite aetiologic factor could be demonstrated. The case was treated with definitive irradiation with excellent immediate response.

Electron beam irradiation in treatment of skin carcinoma.

Thirty seven cases of carcinoma of skin treated with electron-beam irradiation over a period of three years have been analysed retrospectively. Majority of lesions were in head and neck and basal-cell carcinoma was the commonest histological type. Of twenty-one patients followed, seventeen (81%) achieved complete remission and remained disease free for a period of one to three years. Cosmetic results were excellent. Role of electron-beam in the management of these superficial cancers and its advantage over the conventional radiation therapy methods have been highlighted. Radiation therapy utilising electron-beams form a very useful modality in the management of skin cancers, especially those arising in head and neck.