American comedy duo Cheech and Chong had to cancel their Australian tour as Tommy Chong is getting treated for rectal cancer.

The veteran comedians were about to fly to Brisbane on Thursday for their ‘Up In Smoke Greatest Hits’ tour.

It was told that Chong was diagnosed with prostate cancer in 2012, and in 2013 said he had defeated the disease.

The 77-year-old has now revealed through a Twitter post that the cancer has returned in a different form.

His Tweet read, “I have good news and bad news. First the bad news, the cancer came back and it's a real pain in the butt. The good news is I now have to use more marijuana to treat the cancer”.

The comedian also told that he would very soon be documenting his cancer battle in a podcast, and thanked fans for their support.

People who purchased ticket for Cheech and Chong's Australian Tour are being advised to contact their point of purchase for a refund.

Chong and Marin gained fame in 1971 with their comedy album Cheech and Chong and earned a reputation for smoking pot with their films Up in Smoke and Nice Dreams.

First breaking up in the late 1980s, the duo reunited decades later for a comedy tour, Cheech Cong: Light Up America’. A documentary film of their first tour in 25 years was released in 2010.