Cancer can nausea both directly and indirectly.
Directly, tumours can cause nausea. Nausea can be triggered via the stomach or gut and in the brain. Cancers that obstruct or put pressure on these areas, such as the bowel passage, or brain, can cause persistent nausea; this persistent nausea can be the symptom that causes people seek a specialist.
Indirectly, there a multitude of ways that can cause nausea in a cancer setting.
Anxiety caused by a cancer diagnosis can you feel uneasy and sick. Relaxation techniques and mindfulness have been found to alleviate nausea caused by anxiety. Radiotherapy and Chemo, treatments for many cancers, can cause the side-effect of nausea. If having radiotherapy to the stomach or area around the stomach, damage to the tissue can cause nausea. The same can occur for those requiring whole brain radiotherapy or total body irradiation. Chemo causes nausea as the body identifies it as something that should be not there. Fortunately, in the last ten years, there have medical advances in anti-emetic drugs. Anti-emetic drugs are a group of drugs designed specifically to inhibit and decrease the feeling of nausea. They have been developed so people are able to tolerate treatment better.
Cancer and its treatments can also cause underlying problems with your health, such as pain, poorly controlled blood sugars, or issues with your heart. This may require you to start medications that you have not had before. Some of these can lead to feeling queasy. Morphine, a commonly prescribed medication for pain relief, for example, can cause nausea if the dose is not properly titrated.
Lastly, cancer can cause something called anticipatory nausea. Anticipatory nausea occurs when you expect to become nauseous, for example, before treatment. Knowing you have been nauseous during a previous experience causes you to become nauseous even if the trigger (such as chemotherapy), has not been administered yet.