The findings underscore the need for targeted surveillance, especially for prostate, lung, breast and blood cancers, researchers say.
Bowel cancer survivors are at a greater risk of developing subsequent cancers, South Australian data shows.
The Flinders University study analysed four decades of data from almost 27,000 colorectal cancer survivors in the South Australian Cancer Registry and found rates of multiple primary cancers (MPCs) were significantly higher than the general population.
“While patient outcomes have improved over time, CRC survivors already face an increased risk of developing one or more cancers in another part of the colon or other primary sites,” study leader Mulugeta Melku, PhD candidate from the Flinders Health and Medical Research Institute (FHMRI) Bowel Health Service, told media.
One in six CRC survivors developed multiple primary cancers (MPC), at an average of 6.4 years after the index case. Almost all were diagnosed at least six months after the index cancer.
The most common MPCs that later developed were prostate cancer, subsequent colorectal cancer, lung cancer, breast cancer, haematological malignancies, urinary tract organ cancers and skin melanoma.
The researchers also found that the incidence of MPCs grew over the years.
“This study shows that CRC survivors are at increased risk of subsequent cancers compared to the general population, highlighting the need for targeted surveillance, particularly for early detection and treatment of prostate, lung, breast and blood cancers,” he said.
The authors noted that five-year survival for CRC has grown from around 55% to 71% over the last three decades.
“Estimating the incidence, trend and risk of other kinds of MPCs after a diagnosis of CRC will help service delivery, testing and treatment in the coming years, as the population continues to age and survivors live longer,” senior researcher Associate Professor Erin Symonds, gastroenterology researcher from the Southern Adelaide Local Health Network, told media.
In further research, the authors looked at risk factors for developing another cancer after bowel cancer.
“Male sex, older age (>65 y), early-stage cancer, and loss of mismatch repair (MMR) protein expression were associated with an increased risk of developing MPCs,” they wrote.
