Stem cells may be responsible for tumors, according to two separate studies published on Sunday.

Canadian and Italian researchers both found that specialized colon cancer stem cells appeared to be the sources of colon cancer tumors in mice.

Their findings, published in the journal Nature, support the idea that future cancer treatments will have to target cancer stem cells, instead of the type of wide array treatments used today.

Similar findings have been seen for leukemia, breast and brain cancers, but the two studies are the first to show cancer stem cells are also responsible for colon tumors.

“Colon cancer is one of the best-understood neoplasms (tumors) from a genetic perspective, yet it remains the second most common cause of cancer-related death (in Canada), indicating that some of its cancer cells are not eradicated by current therapies,”

“These new studies demonstrate that a small number of colon cancer cells, distinct from those that make up the bulk of a tumor, initiate tumor growth,” Nature said in a statement.

It may be possible to design drugs that attack only those cells, and thus treat colon cancer in a way that better affects the tumors without hurting healthy cells, the researchers said.