Early cancer detection is critical

In the first survey of its kind, the National Cancer Center has disclosed that people newly diagnosed with cancer have a 58 percent chance of surviving for 10 years. The data should not lead patients to feel either pessimistic or optimistic about their prospects, but rather serve as a guide for them on how to achieve the best results in battling the disease.

The center analyzed the cases of some 35,000 cancer patients who were diagnosed between 1999 and 2002 at 16 facilities belonging to the Japanese Association of Clinical Cancer Centers. While the average survival rate in all types of cancers for five years is 63.1 percent, the survival rate 10 years after the diagnosis slightly falls to 58.2 percent.

How people feel about the figures — whether they think they are high or low — may depend on their individual situations and their views of life. But it is important to note that the survival rate — and the change in the rate after five years and 10 years — differs greatly according to the type of cancer as well as when the patients are diagnosed and how they are treated. That information can help patients learn what they need to do to increase their chances of survival.

For example, the survival rate for stomach cancer goes down from 70.9 percent after five years to 69.0 percent after 10 years. But the drop in the rate for breast cancer patients is 8.3 points — from 88.7 percent to 80.4 percent — and that for liver cancer is 16.9 points — from 32.2 percent to 15.3 percent. This shows that some cancer patients who have survived five years need to do more to keep tabs on their health through regular checkups than patients suffering from other types of cancer.

The data also show that if cancers are discovered at stage 1, the patients’ five-year survival rate is 90.1 percent and their chance of survival after 10 years is still high at 86.3 percent. But the corresponding rate is much lower if the cancer is found at stage 3 (with metastasis to lymph nodes) and stage 4 (with metastasis to other organs). For stage 3 cancers, the five- and 10-year survival rate is 46.0 percent and 39.2 percent, respectively, and 17.4 percent and 12.2 percent for stage 4 cancers. The 58 percent 10-year survival rate should not lead people to generalize that 40 percent of all cancer patients will die within 10 years of their diagnosis. The data shows, for example, that a stomach cancer patient who has fought the disease for five years with medical treatment has a 99 percent chance of surviving for another five years. These findings underline the importance of detecting and treating cancer as early as possible.

As one would expect, the survival rate for hard-to-cure cancers is low. The five-year and 10-year chance of survival for pancreas cancer patients, for example, is 6.5 percent and 4.9 percent, respectively. But the main reason why is that these cancers are difficult to detect at an early stage. Cancer researchers should strive to make progress on this front.

Cancer has been Japan’s leading killer since 1981. It claimed the lives of roughly 370,000 people in 2014, or 29 percent of a total 1.27 million deaths. Normally, even if cells become cancerous due to such reasons as damage to genes, the immune system prevents the outbreak of disease. But as people get older, their immune systems grow weaker and it becomes easier for cancerous cells to multiply. As the graying of the nation progresses, it is estimated that half the population will suffer from cancer at some point. Thus it is critical for people to receive regular medical checkups as they grow older to detect cancer as early as possible.

Cancer treatment is making steady progress and the survival rate for all types of cancer will certainly rise in the future. For example, the 10-year survival rate for liver cancer is 15.3 percent, but rapid progress is being made in the development of methods to prevent and cure hepatitis infections, which can lead to liver cancer. Thus the survival rate does not determine how much time is left for each individual patient — that depends on what kind of treatment the patients and their doctors choose and how they battle the disease.

  • Joe Kurosu, M.D.

    Not sure I agree with this piece which plays into the 「早期発見・早期治療!!」mantra. Did they consider lead-time bias? There are downsides to early detection such as the stress of a cancer diagnosis, additional testing and treatment for a cancer that may never cause symptoms or be the cause of death in that individual. Screening must also be distinguished from follow up testing for those already diagnosed with cancer…two completely different things.

    I would recommend that the editor(s) read some of the writings of Dr. Gilbert Welch. “Should I Be Tested for Cancer?: maybe not and here’s why” (University of California Press, 2004), in particular.