The finding has them excited about the prospect of using the drugs -- called bisphosphonates -- to help prevent cancer in healthy people, but other experts are less enthusiastic.
"The lower risk of colorectal cancer risk seen among bisphosphonate users in this study is intriguing," Eric Jacobs of the American Cancer Society, who wasn't involved in the study, told Reuters Health by e-mail.
"However, these results should be interpreted with caution and require confirmation by additional studies."
The new work looked at 933 women with colon cancer, whose average age was just over 70. The researchers then found a comparison group of women without the disease, who matched the first group in age, ethnicity and clinics where they received treatment.
Earlier studies have found that women taking bisphosphonates have a lower risk of breast cancer. But it was unclear if that effect could be chalked up to the drugs, because the condition they are meant to treat -- bone thinning, or osteoporosis -- is tied to low estrogen levels, which also cuts breast cancer risk.