Drinking one to four or more cups of coffee a day may help people with advanced colorectal cancer live longer and slow the progression of their disease. The finding, from a study by the Boston-based Dana-Farber Cancer Institute, was based on about five years of data from 1,171 people treated with chemotherapy for colorectal cancer that had spread, referred to as Stage 4 cancer. Overall, as coffee consumption increased, so did the benefits, and whether the coffee was caffeinated or decaffeinated made little difference, according to the research published in the journal JAMA Oncology. During the study period, the cancer was 5 percent less likely to worsen for people who drank one cup of coffee a day, compared with those who did not drink coffee, 18 percent less likely for two to three cups daily and 22 percent for four or more cups a day. As for survival, those who drank four or more cups daily increased their survival rate by 36 percent compared with nondrinkers. One cup a day yielded a 7 percent increase, and two to three cups increased the survival rate by 18 percent. Study participants who drank the most coffee survived for about 39 months compared with 31 months for those who drank none, a Dana-Farber researcher said. Although research has not determined why coffee might slow the progression of deadly colorectal cancer, cancer experts theorize that it may be related to the antioxidant, anti-inflammatory and insulin-sensitizing effects of compounds found in coffee. Research has suggested that coffee may lower risk for some other cancers. U.S. Dietary Guidelines consider moderate coffee consumption — described as three to five cups a day — safe and healthy for most people. But problems can develop for people sensitive to caffeine, such as headaches, insomnia, dizziness and more.