Research is always being done in the area of stomach cancer. In addition to looking for the causes and ways to prevent stomach cancer, scientists continue to research improved treatments.
Risk factors
Diet
Research has clearly shown that differences in diet are an important factor in explaining variations in stomach cancer risk around the world. Recent research in countries with relatively low stomach cancer risk has provided some insight into risk factors. Diets high in preserved meats and low in fresh fruits and vegetables have been linked with higher risk.
Some studies have found that a diet high in red meat is another possible risk factor. Eating red meat an average of about twice a day seems to raise the risk of stomach cancer. This risk is increased even more if the meat is barbecued and well done.
Helicobacter pylori infection
Recent studies have shown that certain types of H pylori (especially the cagA strains) are more strongly linked to stomach cancer. Some inherited traits related to blood groups may also affect whether someone infected with H pylori will develop cancer. Further research is needed to help doctors determine how to use this information to test which people might be at higher risk for developing stomach cancer. Recent research has also studied the interaction of H pylori infection with other risk factors. For example, they have found that a healthy diet is especially important for reducing stomach cancer risk for people infected with H pylori.
Chemoprevention
Chemoprevention is the use of natural or man-made chemicals to lower the risk of developing cancer. Two types of chemicals might be useful in preventing stomach cancer: antioxidants and antibiotics.
Antioxidants
Many cancer-causing factors cause changes in cells that form a type of chemical called a free radical. Free radicals can damage important parts of cells such as genes. Depending on how severe the damage is, the cells may die or they may become cancerous.
Antioxidants are a group of nutrients and other chemicals that can destroy free radicals or prevent them from forming. These nutrients include vitamin C, beta-carotene, vitamin E (alpha-tocopherol), and the mineral selenium. Studies that have looked at using dietary supplements to lower stomach cancer risk have had mixed results so far. There is some evidence that combinations of antioxidant supplements may reduce the risk of stomach cancer in people with poor nutrition to begin with. Further research in this area is needed.
Antibiotics
Studies are being done to see whether antibiotic treatment of people who are chronically infected by Helicobacter pylori will help prevent stomach cancer. Some studies have found that treating this infection may prevent pre-cancerous stomach abnormalities, but more research is needed.
Although not truly chemoprevention, antibiotics may help prevent stomach cancer from recurring in some cases. Researchers have shown that antibiotics may lower the risk that the cancer will come back in another part of the stomach in people who have been treated with endoscopic resection for early stage stomach cancer. Unfortunately, in the United States these cancers are more often found at a later stage, so it's not clear how useful these results might be here.
Aspirin
An early study looked at giving aspirin to patients who had cancer of the upper part of the stomach (the cardia) after surgery. The patients who took aspirin were more likely to be alive 5 years after diagnosis than the patients that didn't. This is being looked at further in larger studies.
Staging
Sentinel lymph node mapping
Doctors are trying to identify the spread of stomach cancer to lymph nodes using this technique, which has proved very successful in melanoma and breast cancer. In sentinel lymph node mapping, the surgeon injects a blue dye and/or a radioactive tracer substance into the cancer. These concentrate in the lymph nodes that would be the first site of cancer spread. Doctors can remove these lymph nodes and look for cancer. If no cancer is found in those lymph nodes, then the cancer is unlikely to have reached others, and a full lymph node removal might not be needed. If cancer is present in the sentinel lymph node(s), then all the lymph nodes would still need to be removed.
In one study that used this technique for stomach cancer, it helped the surgeon find more lymph nodes to remove. Also, the lymph nodes that were removed were more likely to contain cancer cells. Still, this technique is still being studied in stomach cancer and is not yet ready for widespread use.
Treatment
Laparoscopic surgery
Laparoscopy is commonly used to help stage (determine the extent of) stomach cancer. In countries such as Japan, doctors are now studying the use of laparoscopic (keyhole) surgery to remove small stomach cancers. In this technique, the surgeon creates several small holes in the abdomen, each about an inch long. Special long, thin instruments are inserted into these holes. One of the instruments has a small video camera on the end. The others are used to cut, staple, or sew sections of the stomach.
One of the advantages of this type of surgery is that it does not require a large incision in the abdomen, so recovery time is usually quicker. In one study, laparoscopy seemed to be as effective as standard surgery. Still, it is not widely used to treat stomach cancer in the United States, and more studies may be needed to prove that it is as good as the standard approach.
Chemotherapy drugs and combinations
Some studies are testing new ways to combine drugs already known to be active against stomach cancer or other cancers. Newer chemotherapy (chemo) drugs are also being studied. For example, S-1 is an oral chemo drug related to 5-FU. This is an active drug for stomach cancer that is commonly used in some other parts of the world, but it is not yet available in the United States.
Other studies are testing the best ways to combine chemo with radiation therapy, targeted therapies, or immunotherapy. A good deal of effort is being directed at improving the results of surgery by adding chemo and/or radiation therapy either before or after surgery. Several clinical trials of this approach are in progress.
New ways of giving chemo are also being studied. For example, some doctors are looking at infusing chemo directly into the abdomen (intraperitoneal chemotherapy) to see if it might work better with fewer side effects.
Targeted therapies
Chemo drugs target cells that divide rapidly, which is why they are often effective against cancer cells. But there are other aspects of cancer cells that make them different from normal cells. In recent years, researchers have developed several new targeted drugs to try to exploit these differences. Targeted drugs generally do not have the same types of severe side effects as chemo drugs.
An example of a targeted therapy is a drug called bevacizumab (Avastin®). This drug is thought to work by affecting the blood vessels that supply tumors. Some small, early studies have found that when this drug is combined with chemo, it seems to work better than chemo alone for stomach cancer. Larger studies are now trying to confirm this finding. Bevacizumab is already FDA-approved to treat some other cancers.
Cetuximab is a drug that targets EGFR, a protein that seems to help some cancers grow. This drug has shown encouraging early results when combined with chemo for advanced cancers of the stomach and esophagus. It has also helped some patients when given by itself (without chemo) Studies are being done to confirm these findings. Cetuximab (Erbitux®) is already FDA-approved to treat colorectal cancer and some other cancers.
Other targeted agents that are FDA-approved for other types of cancer have also shown encouraging early results in studies for stomach cancer. These include bortezomib (Velcade®), everolimus (Afinitor®), sunitinib (Sutent®), and sorafenib (Nexavar®), among others.
Most of the research in this area is looking at combining targeted agents with chemotherapy or with each other.
Immunotherapy
Immunotherapy is an approach to treating cancer that uses drugs to try and help the body's immune system fight the cancer. A Korean study showed that combining chemotherapy with an immunotherapy called polyadenylic-polyuridylic acid (poly A:U) slowed the gastric cancer from returning when given as adjuvant therapy after surgery. It also helped some patients live longer.
If you want to search for clinical trials in your area, contact the American Cancer Society at 1-800-227-2345 or visit us on the Web at www.cancer.org/clinicaltrials.
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