Survival And Clinical Characteristics Of Patients With Multiple Primary Cancers: A Hospital-Based Study

Aim: Multiple primary cancers (MPCs) are a group of rare tumors of increasing incidence in recent years. Many issues in terms of epidemiologic features, pathogenesis, and treatment of MPCs are not well understood. Moreover, little data are available in China. Therefore, we aimed to analyze the association between clinical characteristics and prognoses of Chinese patients with MPCs to assess their impact on patient survival. Methods: We examined the incidence, clinical characteristics, and survival in 316 MPC patients. Cox proportional hazards analysis was used to identify independent prognostic factors. Results: Of all patients, 286 developed two primaries and 30 developed three or more primaries. The primaries were synchronous in 87 and metachronous in 229 patients; 136 patients survived, 169 died, and 11 were lost to follow-up. The median overall survival 1 (interval between the first cancer diagnosis and death, or the end of follow-up, OS1) was 66 months; the median overall survival 2 (interval between the second cancer diagnosis and death, or the end of follow-up, OS2) was 22 months. The median OS1 was longer in patients with metachronous primaries (84 months) than in those with synchronous primaries (25 months). The 5-year survival rates were 70.7% and 21.8%, respectively. For metachronous primaries, the median OS1 was 132 months in patients with > 5-year interval and 52 months in patients with < 5-year interval between the first and second primaries. Differences between the groups were significant (P < 0.05). Sex, interval between the first and second primaries, and initial cancer stage were significantly associated with OS (P < 0.05). Conclusions: Sex, interval between the first and second primaries, and initial cancer stage are independent prognostic factors in MPC patients. Additional tumors in cancer patients may be metastatic or novel lesions. Therefore, the possibility of metachronous or synchronous malignancy should be considered. Postoperatively, a prolonged follow-up is necessary.