Younger adults at greater risk of regional, distant rectal cancer

More and more young patients are developing regional and distant rectal cancer, a US study has found. Although patient age significantly predicts survival, chemotherapy seems ineffective in younger patients with localized and regional disease.

The authors extracted data on young-onset (under 45 years) rectal cancer between 2000 and 2016 from the Surveillance, Epidemiology, and End Results Registry (SEER). They identified 10,375 patients with young-onset rectal cancer, of whom 54.7 percent were male. Median age at diagnosis was 40±5.7 years.

Between 2000 and 2016, the overall age-adjusted incidence of rectal cancer was 1.24 per 100,000 per year, with the incidence increasing with age: the highest occurring in the 40–44 years age group.

Rectal cancer incidence rose by approximately 2.29 percent during the study period. At presentation, most tumours were moderately differentiated (30.8 percent), and the most common stage was stage 4 (48.3 percent). Cause-specific survival was 93 percent at 1 year and 72 percent at 5 years.

In Cox proportional hazard models, chemotherapy resulted in higher mortality in patients with localized cancer (hazard ratio [HR], 2.88, 95 percent confidence interval [CI], 2.04–4.08; p<0.001) and failed to significantly improve mortality outcomes in regional cancer patients (HR, 0.89, 95 percent CI, 0.70–1.04; p=0.116). On the other hand, chemotherapy reduced deaths in those with distant cancer (HR, 0.62, 95 percent CI, 0.56–0.70; p<0.001), but this benefit occurred mostly in patients aged ≥35 years.

Notably, surgery led to improved survival across all cancer stages.