Broca also spent many of his earlier years researching cancer. His wife had a known family history of carcinoma, and it is possible that this piqued his interest in exploring possible hereditary causes of cancer. In his investigations, he accumulated evidence supporting the hereditary nature of some cancers while also discovering that cancer cells can run through the blood. Many scientists were skeptical of Broca's hereditary hypothesis, with most believing that it is merely coincidental. He stated two hypotheses for the cause of cancer, diathesis and infection. He believed that the cause may lie somewhere between the two. He then hypothesized that (1) diathesis produces the first cancer (2) cancer produces infection, and (3) infection produces secondary multiple tumors, cachexia, and death.”