People who survive colorectal (bowel) cancer - the second most commonly diagnosed type of cancer in Ireland - are at an increased risk of going on to develop cancer again, a new study has found.

More than 2,200 people are diagnosed with colorectal cancer in Ireland every year. It is also the second biggest cancer killer here.

According to US scientists, previous research has indicated that people who develop this type of cancer are at an increased risk of developing cancer again, so they set out to see whether this risk was dependent on where the original cancer was located - in the colon or rectum.

They also wanted to determine whether colorectal cancer survivors were at an increased risk of any particular cancers.

The scientists analysed 12 cancer registries containing the details of people who had been diagnosed with colorectal cancer between 1992 and 2009.

They found that people who had survived colorectal cancer had, overall, a 15% increased risk of developing cancer a second time compared to people in the general population. This risk related to any type of cancer.

However, this risk increased depending on where the cancer was located. Those who developed cancer in the transverse to descending region of the colon had the highest risk of going on to develop cancer again - a 30% increased risk. They also had a two-to-three-fold increased risk of developing colorectal cancer for a second time.

Meanwhile, the scientists also found that the risk of developing small intestinal cancer was particularly high among colorectal cancer survivors. In fact, people who had survived the disease had a four-fold increased risk of going on to develop this type of cancer, irrespective of whether their original cancer had been located in the colon or the rectum.

"To our knowledge, this is the first study to look at risk of second cancer according to the specific anatomic subsite of a prior colorectal cancer. In the long-term, these findings may be useful in guiding strategies for cancer screening and surveillance after a first colorectal cancer diagnosis," commented Dr Amanda Phipps of the Fred Hutchinson Cancer Research Center in Seattle.

Details of these findings are published in the journal, Cancer.