Multiple colorectal cancers in the elderly: a retrospective study of both surgical and autopsy cases

Multiple primary cancers are not rare events in the large intestine, and account for approximately 5-7% of patients with colorectal cancer (CRC). There are few reports demonstrating clinicopathologic features of multiple CRCs in the elderly.

We clinicopathologically investigated 947 surgical patients and 362 autopsy samples from patients aged 65 years or more with CRC, including 81 surgical and 34 autopsy cases of multiple CRCs. We compared the data in the very old group (age > or = 85 years) with those of the younger age groups, i.e., a young-old group (65-74 years) and a middle-old group (75-84 years).

The proportion of multiple CRCs was 8.6% (81/947) in the surgical patients and 9.4% (34/362) in the autopsy cases, with no significant difference among the three age groups. Similar site distributions and sex ratios, indicating proximal shift and female predominance with advancing age, were found in multiple and single CRCs, except for autopsy cases with multiple CRCs. Multiple CRCs in nonadjacent segments of the large intestine accounted for 11% (9/81) in surgical cases and 35% (12/34) in autopsy cases. In autopsy cases, the incidence of extracolorectal malignancies in patients with a single CRC was 22% (17/76) in the young-old group, 27% (39/147) in the middle-old group, and 35% (37/105) in the very old group, whereas the incidences in patients with multiple CRCs were 25% (1/4), 11% (2/18), and 50% (6/12), respectively. Regarding the organs with extracolorectal malignancies, the stomach (29%) was most frequent, followed by lung (14%), hematopoietic system (12%), and pancreatobiliary system (10%).

These results indicate that the incidence of multiple CRCs in elderly patients with CRC is approximately 8%-10%, with no age-related difference, while extracolorectal malignancies increase with advancing age.