DEAR MAYO CLINIC: My mother was diagnosed with stomach cancer and has begun chemotherapy. Her doctors say she may need surgery, too. I know this type of cancer is rare, but what are the survival rates for those who do get it? What causes it?
ANSWER: Although it greatly depends on the individual situation, overall the outlook for people diagnosed with stomach cancer is often good after treatment, especially when it is caught early. The exact cause of stomach cancer is not known. However, a number of factors can raise a person’s risk for this cancer, including diet, family history and other medical conditions.
In the United States, stomach cancer used to be much more common than it is today. The number of stomach cancer cases has dropped dramatically within the past few decades, and now it is rare in this country. Stomach cancer is still common, however, in other parts of the world, particularly Japan.
There’s a strong correlation between a diet high in smoked, salted and pickled foods and stomach cancer. Other risk factors include smoking, a diet low in fruits and vegetables or exposure to a fungus-producing carcinogen called aflatoxin. People who have had a bacterial infection with Helicobacter pylori also are at a slightly increased risk.
A variety of medical conditions may raise the risk of stomach cancer, too, including stomach polyps; an infection that involves long-term inflammation of the stomach known as chronic gastritis; and vitamin B12 deficiency due to pernicious anemia. In addition, some genetic mutations that run in families can predispose a person to stomach cancer.
There are several kinds of stomach cancer. The one that makes up the vast majority of cases is adenocarcinoma — stomach cancer that begins in the glandular cells. These glandular cells line the inside of the stomach and secrete a protective layer of mucus to shield the lining of the stomach from acidic digestive juices.
If the cancer has not spread outside the stomach, a typical treatment approach includes chemotherapy followed by surgery to remove the tumor. In many cases, chemotherapy after surgery is recommended, as well.
Research has shown that this approach of using chemotherapy before and after surgery is associated with improved survival when compared to just surgery alone. That’s because with stomach cancer, some tiny cancer cells that may be difficult for a surgeon to see can be effectively eliminated by chemotherapy. Chemotherapy before the surgery also is helpful because it can shrink the tumor, making surgical removal easier.
Chemotherapy drugs used for stomach cancer have improved a great deal in the past 15 to 20 years. Before that, not many chemotherapy agents existed that were proven to be effective in treating stomach cancer. But stomach cancer is usually quite responsive to many of the newer drugs. With the choices available now, doctors are often able to pick a chemotherapy drug that is aggressive against the cancer while minimizing side effects such as nausea, vomiting, weakness and hair loss.
After surgery to remove the cancer and follow-up chemotherapy, your mother will likely have checkup appointments periodically for several years to make sure the cancer is gone. But for now, if she hasn’t already done so, it may be helpful for her to have a conversation with her oncologist to discuss her overall treatment plan. That will give her a chance to ask questions and better understand the long-term outlook for her specific situation. — Robert McWilliams, M.D., Medical Oncology, Mayo Clinic, Rochester, Minn.