Comparison of toxicities of three weekly and weekly cisplatin in concurrent chemo-radiation for head and neck cancers: A retrospective cohort study

SUMMARY Background and Aims: Concurrent chemo-radiation in Head and neck cancer patients offers a significant improvement in local control and overall survival at the expense of added toxicities. In practice, different schedules of Cisplatin are used with concurrent chemo-radiation. This retrospective study aims to compare the toxicity profile of head and neck cancer patients treated with concurrent chemo-radiation using three weekly cisplatin and weekly cisplatin. Methods: This is a retrospective cohort study that included patients with Head and Neck Cancers treated with concurrent chemo-radiation with either of the two schedules of Cisplatin using 100 mg/m² every three weeks or 40 mg/m² every week. Conventional fields were used for radiation treatment. Treatment review charts were used to assess the toxicity of the treatment using RTOG toxicity grading criteria. χ² test or fishers exact test were used to assess the difference between categorical variables. Continuous variables were compared with the two-sample t-test or Mann Whitney test when assumption could not be satisfied. Results: A total of 80 patients, of which 56 patients received the three weekly cisplatin while 24 patients had weekly cisplatin with concurrent chemo-radiation. Skin toxicity of Grade 3 at treatment completion was 5.4% in the three-weekly chemotherapy group, whereas it was 8.3% in the weekly chemotherapy group, which was statistically significant, (p=0.017). Mucous membrane toxicity was not statistically significant in any of the weeks of treatment. Pharyngeal toxicity reached statistical significance at the 4th week of treatment (p=0.015), but after treatment, no significant difference was seen between groups. Similarly, laryngeal toxicities between the groups were not statistically significant even though higher grade 3 toxicities started appearing from 3^rd week. There is a statistically significant difference in terms of toxicities between the two treatment groups in body weight after treatment (p=0.01). When haematological toxicities were considered, hemoglobin toxicity of grade 2 occurred in 16.7% patients in the weekly chemotherapy group, while none at 3rd week which was statistically significant, (p=0.007) while none developed it in the three-weekly group. WBC toxicity showed a significant difference between the groups at the 5th and 6th week of treatment, p=0.001 and p=0.04 respectively with higher toxicity and percentages in the weekly chemotherapy group. Platelet toxicity of grade 2 developed in one patient in the weekly chemotherapy, but no statistically significant difference is seen in any of the weeks. The mean radiotherapy delay in days in the three weekly chemotherapy group was 0.36 day (SD 1.67) whereas in the weekly group was 1.33 days (SD 1.67), was not statistically significant. Treatment response was partial in 5.4% in the three weekly chemotherapy group and 4.2% in the weekly chemotherapy group; the difference noted is not statistically significant. Conclusions: There is heterogeneity in the severity of grade of toxicity within the three-weekly and weekly chemotherapy groups with concurrent chemoradiation. Weekly cisplatin appears more toxic as it is associated with higher grades of toxicities and chemotherapy interruptions. There is no evidence to show that weekly cisplatin is less toxic when compared to three weekly cisplatin in concurrent chemo-radiation for head and neck cancers.