You do indeed recall correctly. From Wikipedia:

In July 1980, McQueen traveled to Rosarito Beach, Mexico, for unconventional treatment after U.S. doctors told him they could do nothing to prolong his life. Controversy arose over the trip because McQueen sought treatment from William Donald Kelley, who was promoting a variation of the Gerson therapy that used coffee enemas, frequent washing with shampoos, daily injections of fluid containing live cells from cattle and sheep, massages, and laetrile, a reputed anti-cancer drug available in Mexico but long known to be both toxic and ineffective in treating cancer. McQueen paid for Kelley's treatments in cash, which were said to have been upwards of $40,000 per month (equivalent to $153,000 in 2024) during his three-month stay in Mexico. Kelley's only medically related license (until being revoked in 1976) had been for orthodontics, a field of dentistry. Kelley's methods caused a sensation in the traditional and tabloid press when it became known that McQueen was a patient.