form of smoked marijuana would prevent vomiting better than swallowing a pill. If vomiting were severe or began immediately after chemotherapy, oral THC could not stay down long enough to take effect. Smoking also allows patients to take only the drug they want, one puff at a time, thus reducing their risk of unwanted side effects. But the long-term harms of smoking outweigh its benefits for all but the terminally ill, the IOM team concluded. Instead, they recommended the development and testing of a rapidonset method of delivering THC, such as an inhaler. Similar devices are now used to administer medicine for asthma and other respiratory disorders and are being developed to deliver pain medication.
Wasting and appetite loss affect most cancer patients. At best these conditions diminish quality of life; at worst they hasten death. Depending on the type of cancer, 50 to 80 percent of patients will develop cachexia, a disproportionate loss of lean body tissue. Cachexia occurs most often during the final stages of advanced pancreatic, lung, and prostate cancers. Proteins called cytokines, produced by the immune system in response to the tumor, appear to stimulate this wasting process.
Cachexia also occurs as a result of HIV infection (see Chapter 5), and both cancer and AIDS patients currently receive similar treatments for the condition. Standard therapies for cachexia include intravenous or tube feeding as well as treatment with megestrol acetate (Megace), an appetite stimulant. If the latter causes patients to gain weight, however, it is mostly in the form of fat—not the lean tissue they would have lost through cachexia.
Marijuana is renowned for its ability to stimulate the appetite, otherwise known as “having the munchies.” This effect is due in large part to the action of THC, which has been confirmed in several studies.8 For example, cancer patients who took THC in the form of dronabinol tended to experience a slowing of weight loss and an increase in appetite.9 A study of AIDS patients, however, indicated that megestrol acetate stimulated weight gain more effectively than THC; when used in combination, the two drugs failed to augment each other's effects.10