Octogenarians present with a less aggressive phenotype of colon adenocarcinoma

Octogenarians constitute a growing percentage of patients diagnosed with colon malignancies. This study aims to determine if the clinical and pathologic presentation of octogenarians with colon cancer differs from that of patients diagnosed at a younger age.

Data were collected retrospectively for all patients diagnosed with colon cancer who underwent resection at a single institution between January 1, 2004 and December 31, 2017; patients with rectal cancer were excluded. Patients were categorized by age at diagnosis: either 50 to 79 years of age or ≥80 years of age; those <50 years of age were excluded because of the greater risk of a hereditary etiology. The primary outcome was the correlation between patient age and pathologic features of the tumor, including tumor size, lymph node metastases, perineural invasion, and extramural venous invasion.

Of 1,301 patients, 329 (25%) were ≥80. Female patients predominated the octogenarian cohort (61% vs 39%; P < .001). Octogenarians presented with larger tumors when compared to patients age 50 to 79 (5.2 cm vs 4.5 cm; P < .001). More patients ≥80 had tumors which were >8 cm (17.3% vs 8.9%; P < .001). Tumors in younger patients were more often detected on screening colonoscopy (23.1% vs 7.3%; P < .001). Regardless of tumor size, octogenarians were less likely to have positive lymph nodes than younger patients (P = .02). In addition, octogenarians were less likely to exhibit extramural venous invasion compared to younger patients across all tumor sizes (P < .001). Younger patients had greater median overall survival (6.4 years vs 4.4 years; P < .001), yet 3-year disease-free survival was comparable between age groups (P = .12).

Octogenarians with colon cancer present with larger tumors but appear to have less aggressive disease, as reflected in a lower pathologic stage, less extramural venous invasion, and less lymph node metastases, than younger patients with similar size tumors. Three-year disease-free survival is comparable between octogenarians and patients aged 50 to 79.