A pair of new studies suggest limitations of adjuvant chemotherapy among older adults with stage 3 colorectal cancer. A phase 2, multi-institutional feasibility study found a completion rate of 67.3%, while a prospective study found that completion was associated with improved disease-free survival.
Both studies were presented in January at the ASCO Gastrointestinal Cancers Symposium 2023.
In HiSCO-04, Japanese researchers found that of 64 older patients with stage 3A colorectal cancer who underwent adjuvant chemotherapy, 53% completed the treatment with an improvement in disease-free survival. Patients who completed adjuvant chemotherapy had better disease-free survival (P = .03), while the survival was lower among those who did not receive adjuvant chemotherapy, and lowest among those who discontinued adjuvant chemotherapy.
“The results showed that adjuvant chemotherapy is not always recommended for elderly patients, and that patients who are able to complete treatment may have a better prognosis for survival. However, the results do not indicate which patients are unable to complete chemotherapy, and it will be necessary to identify patients who are intolerant of chemotherapy,” said the study’s lead author Manabu Shimomura, MD, PhD, an assistant professor of gastroenterological and transplant surgery at the Hiroshima University Graduate School of Biomedical and Health Sciences in Japan.
The study, which was conducted between 2013 and 2021, enrolled 214 patients (99 men, 115 women, 80-101 years old) who were in stage 3 cancer (27 cases 3A, 158 cases 3B, and 29 cases 3C). A total of 41 patients were ineligible for chemotherapy. Of the remaining patients, 65 received adjuvant chemotherapy and 108 did not receive adjuvant chemotherapy.
The 3-year disease-free survival was 63.6%, the 3-year overall survival was 76.9%, and the 3-year relapse-free survival was 63.1%. Thirty-six patients died because of colorectal cancer, and 30 patients died of other causes. There was recurrence in 58 cases and secondary cancers were observed in 17 cases during the 42.5 months–long follow-up period.
There were few reports of serious adverse events, but some cases of treatment discontinuation were because of adverse events.
In a second study presented by Dr. Shimomura’s group, called HiSCO-03, 65 patients (33 female) underwent curative resection and received five courses of uracil-tegafur and leucovorin (UFT/LV).
The completion rate of 67.3% had a 95% lower bound of 54.9%, which were lower than the predefined thresholds of 75% completion and a lower bound of 60%. “Based on the results of a previous ( ACTS-CC phase III ) study, we set the expected value of UFT/LV therapy in patients over 80 years of age at 75% and the threshold at 60%. Since the target age group of previous study was 75 years or younger, we concluded from the results of the current study that UFT/LV therapy is less well tolerated in patients 80 years of age and older than in patients 75 years of age and younger,” Dr. Shimomura said.
The treatment completion rate trended higher in males than females (77.6% versus 57.2%; P = .06) and performance status of 0 versus 1 or 2 (74.3% versus 58.9%; P = .10). The most common adverse events were anorexia (33.8%), diarrhea (30.8%), and anemia (24.6%). The median relative dose intensity was 84% for UFT and 100% for LV.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.