“What percentage of biopsied polyps are cancerous?”

Very low percentage, less than 1%. The chance that a polyp has cancer in it increases with larger polyp size. Cancer will almost never be found in a polyp < 1 cm in diameter. The risk is higher with polyps > 1 cm, but it also depends on the type of polyp. Some polyps even 5 cm or bigger have no cancer. On the other hand, I have seen 1 cm polyps with cancer. Bottom line: if the polyp found is < 1 cm in diameter, then it almost certainly will not have cancer.

Only 5 % of polyps progress to cancer, however, the individual risk for every person varies with the risk factor associated with that person. For instance, if one has a strong history of cancer in the family, the chances of this polyp progressing to cancer will be higher than those people without a family history of cancer. Other risk factors include smoking, fatty diet, inflammatory intestinal conditions, and inherited syndromes such FAP (familial adenomatous polyposis), DIABETES, OBESITY, ETC.

Depending on gender, ethnicity and family history, about 10 to 30 percent.