The fight against cancers of the digestive system – including colorectal, stomach, esophageal, hepatic, and pancreatic cancers – has made significant progress in the past 50 years, especially in prevention and early diagnosis of colorectal cancer, where screening with tests such as colonoscopies is continuing to make a major impact.
“In some areas we have done better than others,” notes Robert J. Mayer, MD, former director of the Center for Gastrointestinal Oncology at Dana-Farber. Mayer, a past president of the American Society of Clinical Oncology (ASCO), led a recently published review commissioned by ASCO.
Today, about two out of three colorectal cancer patients survive five or more years, compared with one in two previously – “a major step forward,” says Mayer, Dana-Farber’s Faculty Vice-President for Academic Affairs.
Fifty years ago, the cause of colorectal cancer was largely unknown, the review noted. Subsequent research has shown that most colorectal tumors develop over many years from pre-cancerous growths called polyps that can be detected with periodic screening examinations such as colonoscopy and sigmoidoscopy. Utilizing these examinations, physicians can remove polyps before they evolve into cancer. In September 2013, a team that included Dana-Farber researchers reported that removing polyps is an effective means of colorectal cancer prevention.
Another Dana-Farber-led study reported that aspirin therapy can extend the lives of patients with colorectal cancer whose tumors carry a certain gene mutation.
Colon cancer that has metastasized is not usually curable, but Mayer notes that “the median survival has increased from six months when I was in training to 30 months today – a five-fold improvement.”
Mayer points out that the gains being made in preventing colorectal cancer haven’t been shared equally across society. “There has been more improvement in certain ethnic and socioeconomic populations than others, and we need to correct these discrepancies” by working toward universal access to screening and preventive treatment, he says.
As for other GI cancers: “We have done a little better in cancer of the stomach and esophagus, and in pancreatic cancer, where the median survival has gone from four months to 12 or 14 months; “something is moving a little bit, finally,” Mayer acknowledges. A Dana-Farber-led study led to the approval in April of the first targeted drug for advanced stomach cancer after standard therapy has failed.