It is a disease that strikes tens of thousands of Iranians each year, but for 300 pupils news that their teacher had cancer prompted an unusual response -- they shaved their heads in sympathy.
"They did it out of respect to a teacher and a champion," Abdollah Jafari, an education official in Hamedan province who witnessed the pupils' en-masse gesture after morning classes on Wednesday, told Mehr news agency.
Pictures on state media showed the teacher, Mohammad Reza Ghaderi, a former top cyclist and national champion several times in the 1990s, surrounded by dozens of smiling children who now had matching bald heads.
After a cycling career that included appearances in major championships, Ghaderi, now 36, became a physical education teacher and now works at Ayatollah Masoumi School in Hamedan, around 300 kilometres (190 miles) from Tehran.
"I am so happy to have the pupils' affection and love. I feel God has given me a new life," he was quoted as saying by the agency.
The report did not specify what kind of cancer he was suffering from.
One of his friends arranged the head-shaving ceremony.
"Mohammad Reza spends the money he earns from teaching on buying balls, bicycles and sports wear for his pupils. He loves his pupils," said the friend, Majir Khezriyan.
"I wanted to lift his morale so I talked to the school's officials and they welcomed the idea," he added.
Cancer is the third-highest cause of death in Iran and mortality rates have risen in recent years.
The chairman of the Cancer Research Center of Iran, Mohammad Esmail Akbari, told state media in January 2014 that 41,000 Iranians die from different cancers each year.
Around 85,000 new cancer sufferers are diagnosed annually, he said at the time, with 18 percent of cases relating to children and 50 percent of those cases become fatal.
Air pollution from substandard fuel used in cars and at power-generation facilities is thought be a major cause in Iran's rising cancer rates.