The new drugs work by destroying a protein called the EGFR, which naturally occurs in the skin, but also helps cancer cells thrive. In the top four deadliest cancers — lung, breast, colorectal and pancreatic — cancer cells start churning out huge amounts of EGFR to feed themselves and self propagate. The drugs that attack EGFR are prescribed for patients — about 100,00 so far — whose cancer has not responded to conventional chemotherapy.

But EGFR, which the drugs so handily wipe out, also is critical for the normal function of skin. Thus, about 90 percent of patients who take it have skin problems so serious that they feel embarrassed by their appearance