The survival advantages associated with National Comprehensive Cancer Network (NCCN) guideline–driven care were not realized in younger patients with stage II and stage III rectal cancer, according to the results of a study published in Cancer.
“For stage II and III disease, younger patients are more likely to receive NCCN guideline–driven care (chemoradiation and surgical resection), but this does not seem to affect their survival,” wrote Andrew Kolarich, BS, of the University of Florida College of Medicine, and colleagues. “In contrast, older patients show a large and significant survival benefit from it.”
According to Kolarich and colleagues, this and other data from the study support the idea that “early-onset rectal cancer may differ in its biology and response to therapy, as has been previously shown in colon cancer.”
In contrast to older patients, the incidence of rectal cancer in patients younger than 50 years is increasing. Existing treatment guidelines for rectal cancer have been established using data from clinical trials that enrolled predominantly older patients.
In order to test if the biology of younger patients with rectal cancer differed from older patients, Kolarich and colleagues compared survival patterns in patients stratified by NCCN guideline–driven care. They used data from the National Cancer Data Base on 43,106 patients treated with transabdominal resections with negative surgical margins for stage I to III rectal cancer between 2004 and 2014. Twenty-one percent of patients were younger then 50.
Current guidelines establish the standard of care as surgical resection alone for stage I disease, and neoadjuvant chemoradiation with subsequent resection and systemic chemotherapy for stage II and stage III disease.
In comparison to older patients, younger patients were more likely to be female and African American, Hispanic, or Asian. In addition, they were more likely to be uninsured, have fewer comorbid conditions, more likely to live in a metropolitan area, have higher income, and to have traveled further for medical care at integrated or academic cancer centers compared with older patients.
Patients younger than 50 were more likely to be diagnosed at a later stage; 40% of younger patients compared with 31% (P < .001) of older patients were diagnosed at stage III.
Both short- and long-term outcomes were significantly better for younger patients compared with older patients. Patients younger than 50 were more likely to receive radiation outside of NCCN guidelines for stage I disease (41.9% vs 31.7%; P < .001), and more likely to receive NCCN-suggested chemoradiation for stage II or III disease (93.6% vs 88.1%; P < .001).
In addition, younger patients had shorter hospital stays (P < .001), better short-term mortality, and better long-term survival rates compared with older patients.
Among older patients, survival outcomes improved with the use of NCCN–guideline driven care for stage II or III disease. However, treatment with neoadjuvant chemoradiation for stage II or III disease was not associated with an overall survival advantage in younger patients.
“These data may help to stimulate future trial proposals to investigate the possibility of the exclusion or selective use of adjuvant therapies for stage II and III disease,” the researchers wrote.