Chemotherapy may be overused in young and middle-aged colon cancer patients

Last Updated: 2017-02-01

By Marilynn Larkin

NEW YORK (Reuters Health) - Young and middle-aged colon cancer patients are more likely to receive postoperative chemotherapy than older patients, but the additional treatment does not improve survival, researchers say.

Although it has been shown to significantly increase disease-free survival in patients with stage III colon cancer, "less is known about the benefits of adjuvant chemotherapy use in patients with earlier-stage cancers . . . and its use remains controversial for early-stage colon cancer," Dr. Kangmin Zhu of the Walter Reed National Military Medical Center in Bethesda, Maryland and colleagues write in JAMA Surgery, online January 25.

"Nevertheless, a considerable proportion of patients are still receiving this treatment," they add. "It is possible that chemotherapy is overused in clinical practice without substantial gain in survival."

To investigate, the researchers analyzed data on 3,143 patients with primary colon adenocarcinoma (59% male) diagnosed between 1998 and 2007. Patients were grouped based on age at onset: 18 to 49 (young; 671 patients), 50 to 64 (middle-aged; 1,599) and 65 to 75 (older; 873).

Adjuvant chemotherapy was used in 69% of younger patients, 53.1% of middle-aged patients and 42.5% of those who were older.

After adjusting for potential confounders, those in the young and middle-aged groups were two to eight times more likely to receive postoperative systemic chemotherapy compared with those in the older group across all tumor stages.

Specifically, middle-aged patients with stage I (odds ratio, 5.04) and stage II (OR, 2.42) cancers were more likely to receive postoperative chemotherapy compared with older patients.

In addition, younger patients (OR, 2.48) and middle-aged patients (OR, 2.66) were more likely to receive multiagent chemotherapy than were older patients, even though multiagent regimes currently are not recommended for most patients with early-stage colon cancer.

However, adjuvant chemotherapy was not linked with any significant differences in survival, regardless of age.

Dr. Zhu told Reuters Health by email, "While our study suggests the possibility of overuse of chemotherapy among younger colon cancer patients, more research is warranted. Also, further research with regard to colon cancer-specific death as the outcome - rather than all cause-specific death - is needed to confirm our findings."

Dr. Anton Bilchik, who was not involved in the new study, commented, "Registry studies . . . are limited because they are retrospective and do not have details on surgical and pathological quality measures."

"While I agree in general that there may be overuse of chemotherapy in the treatment of colon cancer, the findings of the current study have major limitations and should be interpreted cautiously," said Dr. Bilchik, who is chief of medicine and gastrointestinal research at John Wayne Cancer Institute at Providence Saint John's Health Center in Santa Monica, California.

Dr. Bilchik told Reuters Health that his group has published "several articles that demonstrate how important it is to accurately stage patients and potentially avoid the toxicity and expense of chemotherapy in those who are likely cured by surgery alone."

In one prospective study of patients with optimally staged node-negative colon cancer, his team found that 97% of patients remained disease-free after the primary tumor resection (http://bit.ly/1GDR61A).

SOURCE: http://bit.ly/2jDAS00

JAMA Surg 2017.