Actor Vivek Oberoi says he lost his childhood sweetheart to cancer when he was 18.

"When I was just 18, I lost my first love. My childhood sweetheart since the age of 13 died of cancer, " he wrote on his Twitter page.

The actor, who is the brand ambassador of Cancer Patients Aid Association (CPAA), says by helping those who cannot afford treatments he feels he's honouring his late girlfriend.

"Every time I help CPAA, spend time with the patients going to the hospitals on Rose Day or celebrate my b'day with terminally ill children, I feel I am honouring her memory, " he added.

"I was devastated when I lost her, but by helping save the ones who can't afford the treatment and medicines, I feel she's alive in their smiles.

"My mother taught me - the best way to honour the memory of someone you've loved and lost is to reach out and ease someone else's pain and misfortune, " wrote the actor who is associated with the CPAA for eight years.

The actor is now looking forward to the release of "Prince", which is his first solo hero movie in five years.