A patient who took an anti-cancer drug lost his fingerprints, which caused him to be detained for hours when he tried to visit the United States.

The 62-year-old patient had been taking capecitabine, a follow-up drug for chemotherapy for cancer of the head and neck, Singaporean specialist Eng-Huat Tan and colleagues recounted in a letter to the British journal Annals of Oncology.

Capecitabine's side effects include inflammation of the palms and soles of the feet. The skin can peel, bleed and develop ulcers, and with time can cause fingerprints to be eradicated, Dr Tan said.

The patient, named as Mr S, had been prescribed the drug as long-term maintenance treatment but was unaware this had wiped out his fingerprints.

"In December 2008, after more than three years of capecitabine, he went to the United States to visit his relatives," the letter said.

"He was detained at the airport customs for four hours because immigration officers could not detect his fingerprints."

Foreign visitors arriving at US airports are asked to provide fingerprints which are then matched against a database of visa holders and a list of suspected criminals.

Mr S was eventually allowed to enter after officials were satisfied he was not a security threat, Dr Tan said. He was also advised to travel with a letter from his cancer doctor to explain his fingerprint-free condition.

The letter urged patients who are put on long-term courses of capecitabine to be aware of the unusual side effect.

- AFP