Clinical analysis of multiple primary gastrointestinal malignant tumors: A 10-year case review of a single-center.

Background: Multiple primary malignant tumors (MPMTs) was first described by Billroth as early as 1889, with the first report published by Warren and Gates in 1932. Since then, numerous cases have been reported. A literature review of 1104269 patients with cancer revealed that the incidence of MPMTs ranged from 0.73 to 11.7%. In recent years, however, there has been a significant upward trend in the incidence of this phenomenon, which may be associated with many different factors, including the advancement of modern diagnostic procedures facilitating the examination and diagnosis of more MPMTs, increased exposure to chemotherapy and radiotherapy that exacerbate the risk of new malignant tumors in patients with cancer, and prolonged survival of patients with cancer allowing sufficient time for the development of new primary cancers.

Aim: To analyze the incidence, clinical features, treatment factors, prevalence, and prognosis of patients with MPMTs in the gastrointestinal tract treated in a single center. Additionally, we analyzed the different tumor combinations, time interval between the occurrence of tumors, and staging.

Methods: This retrospective cohort study analyzed 8059 patients with pathologically confirmed gastrointestinal malignant tumors treated at the Gansu Province Hospital in Lanzhou, Gansu, China between June 2011 and June 2020. Of these, 85 patients had MPMTs. The clinical features, treatment factors, prevalence, and prognosis of this latter cohort were analyzed.

Results: The incidence of MPMTs in patients with gastrointestinal malignant tumors was 1.05% (85/8059), including 83 double primary malignant tumors and two triple primary malignant tumors of which 57 (67.06%) were synchronous MPMTs (SMPMTs) and 28 (32.94%) were metachronous MPMTs (MMPMTs). The most frequent associations were found between the rectum colon cancers within the SMPMT category and the gastric-colon cancers within the MMPMT category. For the MMPMTs, the median interval was 53 months. The overall 1-, 3- and 5-year survival rates from diagnosis of the first primary cancer were 91.36%, 65.41%, and 45.97%, respectively; those from diagnosis of the second primary cancer were 67.90%, 29.90%, and 17.37%, respectively.

Conclusion: MPMTs in the gastrointestinal tract have a high incidence and poor prognosis. Thus, it is necessary to perform both gastroscopy and colonoscopy in patients with gastrointestinal tumors. Multidisciplinary comprehensive diagnosis and treatment may improve the diagnosis rate and treatment efficiency of MPMTs.