If you're over the age of 45 and get acute appendicitis you are six times more likely to have underlying colorectal cancer, a new study has found.
The results have led researchers to recommend doctors consider checking for colorectal cancer in older adults following a diagnosis of appendicitis.
Colorectal cancer, also known as bowel or colon cancer, is the second highest cause of cancer death in New Zealand but it can be treated successfully if detected and treated early.
New Zealand has one of the highest bowel cancer rates in the world - in 2011, 3030 people were diagnosed with bowel cancer and 1191 died from the disease.
The study was published in the New Zealand Medical Journal today and headed up by Rebecca Shine, the general surgery registrar at the Bay of Plenty District Health Board.
It found that a presentation of appendicitis in patients over 45 years old may constitute a sign of underlying colorectal cancer.
Patients aged between 45 and 60 with acute appendicitis had more than 17 times more chance of underlying colorectal cancer than would be expected, the study reported. For everyone over 45, there was an overall risk six times greater than expected.
Of the 629 Bay of Plenty patients with a diagnosis of acute appendicitis who were included in the study, 15 were diagnosed with colorectal cancer during the study period - six times more than would be expected given their demographics.
Eight patients were diagnosed with colorectal cancer as a result of tissue samples collected during treatment for appendicitis.
The other seven were found during or after treatment for their appendicitis or other issues. One was diagnosed one month later on follow-up colonoscopy and the other was diagnosed 28 months later because they had abdominal pain.
The remaining five patients were detected a median of 12 months later suggesting these cancers were also present at the time of appendicitis.
The study author concluded the possibility of a co-existent cancer should always be kept in mind when treating patients over 45 who had symptoms of appendicitis and said clinicians should pay particular attention to any factors that may raise the suspicion of colorectal cancer.
The authors stopped short of recommending universal colonic investigation for these patients but said if a person's appendicitis was treated without operating or if their initial tissue specimen revealed malignancy they should be offered it.
Even if tissue samples were benign, doctors should consider whether colonic investigation might be worthwhile, they said.
The study comes as the government begins the roll-out of the national bowel screening programme, piloted by Waitemata District Health Board.
This month free screening began to be offered to anyone between 60 and 74 in the Hutt Valley and Wairarapa.
The programme will be rolled out across the whole country in coming years.
About colorectal cancer
Also known as bowel or colon cancer.
Common symptoms of bowel cancer include a change in your normal pattern of going to the toilet that continues for several weeks and blood in your bowel motion.
People who are diagnosed with bowel cancer, and receive treatment when it is at an early stage, have a 90% chance of long-term survival.