Source of Support: None, Conflict of Interest: None
To increase, the tumour control in advanced head and neck cancers, combined treatment modality like radiotherapy-chemotherapy has been in practice. A chemotherapeutic drug methotrexate has been used along with radiotherapy. The tumour regressions and normal tissue reactions with the combined mode of therapy have been compared with that due to radiotherapy alone. Time dose fractionation concepts of CRE, TDF, ERD were applied to the data. The changes brought about in the a/B values due to the combined action of radiotherapy and methotrexate are obtained from the data. The concept of Radiation Equivalent Chemical (REC) of environmental pollution has been extended to these combination treatments and is termed as Gray Equivalent Chemical (GEC). The patients receiving radiotherapy alone (control group) were treated using 25 to 30 fractions of 2 to 2.2 Gy given once a day with five fractions per week. Experimental groups were given 2.5 mg of methotrexate 2 hrs before the radiation dose. A dose of 2.25 Gy was delivered once a day and total dose was 45 Gy in 20 fractions in four weeks.