Ken Watanabe Diagnosed with Stomach Cancer

Actor Ken Watanabe has had an illustrious career both in his native Japan, as well as in the US. He is known for playing tragic hero characters, such as General Tadamichi Kuribayashi in Letters from Iwo Jima and Lord Katsumoto Moritsugu in The Last Samurai, a role for which he was nominated for the Academy Award for Best Supporting Actor. He is also known for his roles in director Christopher Nolan’s Hollywood films Batman Begins and Inception.

In April 2015, Watanabe made his Broadway debut in the title role in the revival of The King and I. He was nominated for a Lead Actor Tony for his portrayal of the Siamese King, and was scheduled to rejoin the cast in March 2016. However this has been postponed, as the 56-year-old has been diagnosed with stomach cancer. His press agent, Craig Bankey, reported that Watanabe’s cancer had been caught at an early stage and that he had undergone endoscopic surgery. He is recuperating at a hospital in Japan. In a statement, Watanabe said:

“I would like to ask for your understanding that the start of my performance in New York will be a little delayed.”

This is not Watanabe’s first brush with cancer. In 1989, while filming a Japanese film in Canada, he began to feel weak. After he fainted he was taken to a hospital where he got the news that he had acute myeloid leukemia. He received treatment in Japan, and was on the way to recovery when the cancer returned in 1994. He went into remission two years later.

What is stomach (gastric) cancer?

The stomach is a J-shaped organ in the upper abdomen. It is part of the digestive system, which processes nutrients (vitamins, minerals, carbohydrates, fats, proteins, and water) in foods that are eaten and helps pass waste material out of the body. Food moves from the throat to the stomach through a hollow, muscular tube called the esophagus. After leaving the stomach, partly-digested food passes into the small intestine and then into the large intestine.

The wall of the stomach is made up of 3 layers of tissue: the mucosal (innermost) layer, the muscularis (middle) layer, and the serosal (outermost) layer. Gastric cancer begins in the cells lining the mucosal layer and spreads through the outer layers as it grows.

Stomach cancer is the fourth most common cancer in the world. It is estimated that in 2015 there will be 24,590 new cases of stomach cancer in the United States. Since 2005, the number of new cases of stomach cancer in the U. S. has stayed about the same. Men are twice as likely as women to be diagnosed with stomach cancer.

Several types of cancers are found in the stomach:

• The vast majority 90% to 95% of gastric cancers are adenocarcinomas. This cancer develops from the cells that form the innermost lining of the stomach (known as the mucosa).
• Gastric lymphomas account for about 4% of stomach cancers. These are cancers of the immune system tissue that are sometimes found in the wall of the stomach. For the most part, they are Non-Hodgkins lymphomas (NHL) which have originated in the stomach.
• Gastrointestinal stromal tumors (GIST) are rare tumors that seem to start in cells in the wall of the GI tract called interstitial cells of Cajal. Although GISTs can be found anywhere in the digestive tract, most occur in the stomach (60%) and small intestine (25%).
• Carcinoid tumors are tumors that start in hormone-producing cells of the stomach. Most of these tumors do not spread to other organs. About 3% of stomach cancers are carcinoid tumors.

What are the risk factors for stomach cancer?

• Infection of the stomach with Helicobacter pylori (a bacterium believed to be the cause of most peptic ulcer disease)
• Chronic inflammation
• Male sex, especially men of Asian-Pacific, African-American or Hispanic descent
• Age over 65 years old
• History of eating lots of salted, smoked or pickled foods
• Cigarette smoking or alcohol overuse
• Family history of stomach cancer

What are the symptoms of stomach cancer?

Early stomach cancer often does not cause symptoms. As the cancer grows, the most common symptoms are:

• Discomfort or pain in the stomach area
• Difficulty swallowing
• Nausea and vomiting
• Weight loss
• Feeling full or bloated after a small meal (early satiety)
• Vomiting blood or having blood in the stool

How is stomach cancer treated?

Certain factors affect prognosis (chance of recovery) and treatment options, the most important of which are the type of cancer and the stage of the cancer.

When stomach cancer is found very early, there is a better chance of recovery. Unfortunately, stomach cancer is often in an advanced stage when it is diagnosed. At later stages, gastric cancer can be treated but rarely can be cured.

The stages of stomach cancer are determined by how deep the tumor has grown through the layers of the stomach, whether any nearby lymph nodes are also involved and whether the tumor has spread outside of the stomach to distant parts of the body. In stage 0, the tumor is only present in the innermost layer of the stomach, the mucosa. In stage 1, the tumor has extended into the underlying submucosa. Stages 2 and 3 tumors have grown deeper into the stomach wall, and in stage 4, the tumor has grown outside of the stomach.

Five types of standard treatment are used:

• Surgery
• Chemotherapy
• Radiation therapy
• Chemoradiation
• Targeted therapy

Surgery is a common treatment of all stages of gastric cancer. The following types of surgery may be used:

• Subtotal gastrectomy: Removal of the part of the stomach that contains cancer, nearby lymph nodes, and parts of other tissues and organs near the tumor.
• Total gastrectomy: Removal of the entire stomach, nearby lymph nodes, and parts of the esophagus, small intestine, and other tissues near the tumor. The spleen may be removed. The esophagus is connected to the small intestine so the patient can continue to eat and swallow.

Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping them from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy).

Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. Chemoradiation therapy combines chemotherapy and radiation therapy to increase the effects of both. It is often given after surgery to decrease the risk that the cancer will return.

A surprising connection between stomach cancer and breast cancer

About 15-20% of breast cancers are caused by genetic “amplification” of a gene called HER2 that is expressed on the surface of cancer cells. HER2 is part of a family of protein “growth factors” that, when unregulated, lead to abnormal growth, invasion and metastasis, in other words, cancer. Surprisingly, about 20% of stomach cancers are also “HER2 positive.”

HER2 is one of many “drug targets” that have been discovered over the past two decades. Very specific drugs that block HER2 have been developed and are used to tailor (personalize) treatment based on unique characteristics of a patient’s tumor. These treatments tend to have many fewer side effects than traditional chemotherapy.

One type of targeted drug (trastuzumab or HERCEPTIN®) is an antibody that has been manufactured to recognize and attack the HER2 protein and kill cancer cells. The picture shows HER2 in red and trastuzumab in purple and blue (illustration courtesy of Precision Medicine Network).

Trastuzumab is given by injection and is approved by the Food and Drug Administration (FDA) to treat both breast and stomach cancer.

Sources: U.S. National Cancer Institute and National Library of Medicine