For a doctor to tell a patient that he or she has cancer is horrifyingly direct in a culture that values the indirect and the subtle understatement.
In their defence, doctors say that no matter what euphemisms they use, patients suffering from cancer instinctively know it, deep down. But both prefer to live in a realm of half-truths and gentle self-deception.
In a survey last year, a quarter of those asked said they would not like their doctor to tell them if they had cancer, and nearly 60 per cent said they would not tell a relative who was suffering from the disease.
But what works in private life becomes more strained in the public domain. Japan's political world is awash with rumours that Michio Watanabe, the Foreign Minister, has cancer. Little has been said in public. Mr Watanabe says he is recovering from a cold, but no one is convinced.
Mr Watanabe was admitted to hospital last May for what was said to be a gall bladder operation. The first sign it was something more serious came when he was kept in hospital for two months after what should have been a straightforward surgical procedure. When he emerged from hospital, he had lost weight, looked haggard, and announced he would be commuting to parliament from his hospital bed for 'continuing tests and observation'.
After a short trip to the US last month, his condition worsened, and he was readmitted to hospital. Officials said Mr Watanabe was suffering from a cold and exhaustion from his trip. He missed meetings with Boutros Boutros- Ghali, the UN Secretary-General, and Helmut Kohl, the German Chancellor.
Mr Watanabe's condition has become painfully embarrassing. During the parliamentary debates on the budget, he repeatedly excused himself from the chamber and left early, supporting himself against pieces of furniture as he shuffled to the door. With Japan becoming more involved in G7 discussions about Russia, and Tokyo preparing to host a G7 summit in July, muted comments are being made that Mr Watanabe is no longer able to perform the taxing job of Foreign Minister.
Bureaucrats at the Foreign Ministry, who have been staunchly defending their boss's health in public, have been conceding in private since last summer that his condition is serious. Some have even drawn parallels with Shintaro Abe, a former foreign minister who spent months in hospital suffering, officially, from gallstones until he died in 1991 from what was later admitted to have been cancer of the pancreas.
Two reasons seem to be keeping Mr Watanabe in his job despite his obvious distress: personal ambition and a determination not to allow the faction he leads to fall apart. After 30 years in parliament, and 17 years as a cabinet minister, Mr Watanabe is next in line for the prime ministership when it comes up in October. In his weakened state, few think he could get the job. But after three decades of political toil it must be a difficult dream to abandon.
At the same time, there is no obvious successor to Mr Watanabe. If he were to resign now, many members of his faction might be tempted to go in search of another powerful patron who could guarantee funding and some hope of cabinet positions.
Such a break-up would add further to the turmoil and sense of crisis engulfing the ruling Liberal Democratic Party, and party elders must be quietly admiring Mr Watanabe's stoicism for hanging on and maintaining a semblance of stability.