Double versus Single Primary Malignant Neoplasm of Breast and Colorectal Cancer: A Case-Control Study

Breast cancer (BC) and colorectal cancer (CRC) are common in female. This study compared survival time between women affected with both cancers with ones with single BC or single CRC.

Medical records of subjects with both BC & CRC (June 1, 2010, to June 30, 2021) were reviewed. Age-matched subjects who had BC or CRC alone were used as control. Survival analysis using Kaplan-Meier method was performed.

There were 63 double cancers [40 BC first (DBC): 23 CRC first (DCRC), mean age±SD 60.5±9.9 and 60.9±12.2 years] and 76 subjects in single cancer group [53 SBC: 23 SCRC, mean age 57.4±11.3 and 61.1±12.5 years]. The 5-year survival rate of the double cancer group was 74.6% and the single cancer group was 63.2%. D-group had slightly longer survival time than S-group (116.5±4.0 vs. 101.3±5.5, p=0.055). In D-group, the occurrence of addition of other primary cancers were more common (p=0.015). The second cancer occurred 61.7±45.3 months later in DBC group, and 39.1±26.6 months later in DCRC group (p=0.016). SCRC had shorter survival time vs. DCRC group (p=0.031). SBC and DBC had no different in mean survival time.

BC and CRC could occur as a part of multiple primary cancers. Detection of more than one cancer did not lead to decrease survival if the second cancer was early detected and treated. The occurrence of the second cancer might be beyond 5 years after the diagnosis of the first cancer. Thus, longer surveillance may be warranted. Awareness and provision of early screening should be offered to individuals diagnosed with either primary cancer. Detection of more than one cancer did not lead to shorter survival.