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While nausea and vomiting are common symptoms for many patients, patient with cancer often have multiple contributing factors for their nausea, not only from the disease itself but from the treatments. This two-part post will be looking at nausea and vomiting specifically with an eye towards cancer, the first part on chemotherapy-induced nausea and vomiting (CINV) and the second part on other types of nausea and vomiting.

Why does chemotherapy induce nausea and vomiting? There are several different ways this happens. One way is through the “chemoreceptor trigger zone,” or CTZ, which gets triggered by exposure to drugs via the blood and cerebrospinal fluid—this activates the command center for vomiting. The other major way is via damage to the intestines themselves by the chemotherapy; the damage to the gut triggers vomiting, both by sending signals to the brain and back to the gut itself.

CINV is usually categorized by the timing of the nausea/vomiting related to the administration of the chemotherapy—acute (within the first 24 hours of receiving chemotherapy) and delayed (after the first 24 hours ). There can also can be anticipatory nausea and vomiting occurring prior to the chemotherapy (based on a learned response from earlier chemotherapy), but this is less common.

Chemotherapies can be categorized by how “emetogenic,” or vomit-inducing, they are. For example, in lung cancer, the big culprits are cisplatin and carboplatin, as well as cyclophosphamide and doxorubicin. Other agents that are more moderate are alimta (pemetrexed), camptosar (irinotecan), or taxotere. Anti-nausea regimens are generally tailored to match how emetogenic the chemotherapies are.

The current medications used to combat CINV target the specific mechanisms I mentioned above. One major class of medication is the 5-HT3 antagonists, like zofran (ondansetron). This includes all the anti-nausea medicines that end in “-tron”—kytril (granisetron), anzemet (dolasetron), and the newest Aloxi (palonosetron). They are very effective for CINV because they target the specific receptors both in the gut and in the CTZ that trigger nausea and vomiting. The newest CINV medications are the NK1-receptor antagonists, like Emend (aprepitant)—NK1 is another receptor that is a culprit in the brain that mediates the nausea and vomiting response. The other common class of medications used in CINV are the corticosteroids, like prednisone or dexamethasone. While their mechanism of action is not as targeted, they have been well-studied in the management of CINV.

The benzodiazepines, like ativan (lorazepam), have also been used in CINV particularly when to help with some of the activating side effects of dexamethasone (like insomnia or agitation) or when there is an anticipatory component leading to anxiety.

There are non-medication therapies for CINV as well that have been studied. Acupuncture, behavioral therapy, and relaxation therapy have all been shown to have some benefit in CINV. As per Dr. West’s recent post, there is promising research coming out on ginger as well.