Newly developed drugs can increase the chances of helping patients overcome hard-to-cure illnesses such as cancer. Pharmacological breakthroughs are welcome, but new drugs that come out of them tend to be so expensive that their wide use can put a heavy strain on the nation's medical expenses. In approving the use of such drugs, the government needs to take utmost care so that it doesn't sow the seeds of bankruptcy in the nation's public health insurance system.

Under the system, which in principle covers all residents, the Health, Labor and Welfare Ministry's Central Social Insurance Medical Council decides on the prices of drugs that doctors prescribe to patients. For example, Nivolumab, an antibody sold under the trade name Opdivo, carries a price of about ¥730,000 per 100 mg. Ahead of other countries, the Japanese government approved the product in 2014 as a drug for treatment of malignant melanoma, a form of skin cancer.

When Opdivo was put on the Japanese market in 2014, it was estimated that some 470 patients of malignant melanoma will use it. But the potential number of users jumped to the tens of thousands when the government approved the drug for treatment of non-small cell lung cancer last December. This type of lung cancer accounts for about 85 percent of all cases of lung cancer. Last month, the government authorized the drug's use against renal cell carcinoma, a type of kidney cancer, adding an estimated 4,500 patients of the disease to potential users of the drug.