Rectal cancer is more likely to spread to the lymph nodes in younger patients, according to new findings that Fox Chase Cancer Center researchers will be presenting on October 29 at the American Society for Radiation Oncology's 54th Annual Meeting. The results—which are the first of their kind—suggest that doctors should search for spreading more aggressively in these patients.
Once rectal cancer has spread to the lymph nodes, it is more likely to return to the pelvis following surgery. Administering chemotherapy and radiation before surgery reduces that risk, so before the procedure doctors typically perform a scan—ultrasound, PET, or MRI—to search for signs of cancer in the lymph nodes.
These findings suggest that doctors should hunt for affected lymph nodes more aggressively in younger patients, by perhaps performing multiple scans, says study author Joshua Meyer, MD, attending physician in the Radiation Oncology Department at Fox Chase.
"When doctors have younger patients, they might think twice before being confident rectal cancer has not spread to the lymph nodes," says Meyer. "It makes a lot of sense to be more aggressive in checking for lymph node involvement in people younger than 50."
This is the first study to show that age is associated with the risk that rectal cancer will spread to the lymph nodes, says Meyer. The idea for the project came out of an observation by his collaborator Steven Cohen, MD, chief of gastrointestinal medical oncology at Fox Chase, who noticed a couple of young patients with an early stage of rectal cancer that had unexpectedly spread to the lymph nodes—"which is not something one would expect," says Meyer. "Because of that, he said, 'I wonder if the risk of spread is somehow connected to their age.' I said, 'Well, this is something we can test.'"
Indeed, the researchers had access to a massive database of information about cancer patients run by the National Cancer Institute. They reviewed the case history of more than 56,000 patients diagnosed with rectal cancer between 1988 and 2008. Approximately 2% of patients were ages 20-39; 7.5% were in their 40s.
Overall, the younger patients were, the more likely it was that their cancer had spread to their lymph nodes—regardless of the stage of their tumors. For instance, among those whose tumors were the least invasive into the rectal wall (stage T1), 22.3% of 20-39 year-olds had affected lymph nodes, versus only 10.8% of patients ages 60-69. The same differences appeared in people whose tumors were more invasive—in T3 tumors, the most common presentation, 60.7% of younger patients had tumors that had reached the lymph nodes, versus 49.4% of those in their 60s.
It's not clear why age might influence the spread of rectal cancer, notes Meyer. Perhaps the tumors of younger patients are simply biologically different from those of older patients, rendering them more likely to spread, he speculates.
Even though the researchers reviewed data collected from tens of thousands of patients, these initial findings should be followed up by more research, notes Meyer. "Since this is a first study, I don't think you can definitively say that age is directly related to risk of lymph node involvement in rectal cancer. But it is something one should keep in mind."
Consequently, when young people are diagnosed with rectal cancer, it makes sense to ask their doctors to thoroughly check their lymph nodes for signs of spread before skipping chemotherapy and radiation prior to surgery. "I think it's worth talking about with your doctor."
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