The relationship between the radiation dose of pelvic-bone marrow and lymphocytic toxicity in concurrent chemoradiotherapy for cervical cancer

OBJECTIVE: The purpose of this study is to verify the correlation between medium and low radiation doses of the pelvic-bone marrow and the incidence of lymphocytic toxicity during concurrent chemoradiotherapy for cervical cancer. MATERIALS AND METHODS: This research included 117 cervical cancer patients, who received concurrent chemoradiotherapy. Radiotherapy included external-beam radiation therapy and brachytherapy. The dosimetry parameters include the Volume receiving 5 Gy (V5), 10 Gy (V10), 20 Gy (V20), 30 Gy (V30), 40 Gy (V40), 50 Gy (V50), and the mean dose (D mean) of the bone marrow. Lymphocytic toxicity was calculated from lowest lymphocytic count after two cycles of concurrent chemotherapy. RESULTS: During concurrent chemoradiotherapy, the incidence of lymphocytic toxicity is 94.88%. The incidence of grade 3–4 toxicity is 68.38%. Multivariate analysis findings show that the dosimetry parameters V5, V10, V20, and V30 are significantly correlated with lymphocytic toxicity. The patients are divided into small-volume subgroups and large-volume subgroups based on the cutoff values. The relative risk of both grade 1–4 and grade 3–4 lymphocytic toxicity is significantly lower in the small-volume subgroups than in the large-volume subgroups (P < 0.05). Kaplan–Meier analysis shows that the incidence of both grade 1–4 and grade 3–4 lymphocytic toxicity of the small-volume subgroups is significantly lower than that of the large-volume subgroups (P < 0.05). CONCLUSION: There is a significant correlation between a medium and low dose of pelvic-bone-marrow radiation and incidence of lymphocytic toxicity. Reducing the volume of medium and low radiation doses could effectively reduce incidence of lymphocytic toxicity.