Age Matters in Prognosis of Colorectal Cancer

Age is a prognostic factor for both overall survival (OS) and progression-free survival (PFS) among patients diagnosed with metastatic colorectal cancer, according to the results of a study published in the Journal of Clinical Oncology. The age effect did not vary by the sites of metastases, the type of therapy received, or the mutation status of the tumor.

Compared with middle-aged patients, younger patients had a 19% increased risk of death and a 22% increased risk of progression. The oldest patients in the study had a 42% increased risk of death and a 15% increased risk of progression compared with their middle-aged counterparts. This was most pronounced 1 year after diagnosis. After adjusting for sex; liver, lung, or peritoneal metastases; and performance status, age remained marginally significant for OS (P = .08) and significant for PFS (P = .005).

Cathy Eng, MD, professor in the department of gastrointestinal medical oncology at the University of Texas MD Anderson Cancer Center in Houston, and colleagues analyzed a total of 20,023 patients who participated in 24 first-line colorectal cancer clinical trials that were part of the Aide et Recherche en Cancérologie Digestive (ARCAD) database. Fifteen percent (3,051) of the patients were younger than age 50.

The incidence of metastatic colorectal cancer among younger patients (those younger than 50) has seen an uptick in the last few years, although the proportion is still relatively small (about 4.6%). In the United States, the median age of diagnosis of colorectal cancer is 72 and almost one-third of those diagnosed are older than 80. But the incidence of colorectal cancer has recently been shown to increase by about 1.5% every year for individuals aged 50 or younger, with those between the ages of 20 and 29 having the highest increase in incidence (5.6% per year for women and 5.2% per year for men).

The median age of patients analyzed in this study was 62, and 4% were younger than age 40. Thirty-eight percent of the patients were female.

“In contrast to prior studies, our analyses revealed that age was a significant predictor of OS, with the youngest and oldest patients showing worse survival than patients of middle age, with similar results seen for PFS,” the study authors concluded. The reasons for these differences may be the inclusion of a greater proportion of younger patients in the current study and the evaluation of age as a continuous, rather than a discrete, variable.

The study suggested that both younger and older patients with metastatic colorectal cancer could represent a higher-risk population, according to the study authors. Although younger patients are generally healthier overall at diagnosis, a worse prognosis may reflect a different, more aggressive tumor biology or a general greater tumor burden.