Dr Raymond Yap Colorectal and general surgeon based in Melbourne, Victoria.

First published online on 4 April 2024

BACKGROUND

DESPITE the advances in screening

and management, colorectal cancer remains a significant cause of morbidity and mortality in Australia. Excluding skin cancers, the prevalence of colorectal cancer( CRC) in men and women is only exceeded by prostate and breast cancer respectively, and colorectal cancer is still the second highest cause of cancer-related death after lung cancer. 1

More disturbing has been the accelerated rise of CRC in those aged under 50, with more than 10 % of all bowel cancer diagnoses in this age group.

Bowel cancer is now the 5th most common cause of death( from all causes) in patients between the ages of 25 and 44. 1

There is excellent evidence to support population-based screening for CRC, with three large randomised, multinational trials showing reductions in colorectal cancer-related disease and death utilising faecal occult blood testing( FOBT), and another trial with preliminary results showing similar benefits for colonoscopy. 2, 3

In 2020, the National Bowel Cancer Screening Program( NBCSP) was fully implemented with FOBT recommended every two years for those aged 50-74. Despite this, colorectal screening in Australia remains at about 40 %, well below other population-based screening programs that have weaker evidence-based rationales. 4 There is evidence that screening rates increase with the intervention of GPs and other health professionals. Since then, screening has been expanded to those between 45 and 49 years of age.

GPs play a vital role in the screening, diagnosis, initial management and long-term treatment of CRC. Initial stratification of colorectal cancer risk, based on a range of risk factors, is paramount, followed by appropriate screening and investigation. Survival has slowly increased over the past three decades and now stands at 70 %. 5 Advanced and metastatic CRC treatment options have multiplied, with promising results from new chemotherapy and immunotherapy agents. There is increasing recognition of

the devastating effect of colorectal cancer on patients’ psychosocial wellbeing, and this has encouraged the development of cancer survivorship strategies.

This How to Treat is part one of a two-part series. It covers the diagnosis and investigation of CRC, as well as the common indications for screening and colonoscopy. It aims to refresh GPs’ knowledge regarding the identification of colorectal cancer, and to ensure GPs are able to have effective discussions on colorectal cancer screening. Part two will cover the treatment and management of colorectal cancer, and aims to equip GPs to aid patients in their treatment journey, as well as to identify common complications.

DIAGNOSIS AND INVESTIGATION

Symptomatic patients

THE cardinal symptoms of CRC are

listed in box 1. The combination of these symptoms may be suggestive of CRC; however, all of these symptoms are common in the community and may alternatively indicate

a range of benign conditions. These symptoms may require further investigation and management where indicated.

THE PATIENT WITH RECTAL BLEEDING Isolated rectal bleeding is a common presentation to GPs. In most patients, the cause is likely to be benign and perianal in origin. Because of the prevalence of CRC in Australia, any adult patient who presents with rectal bleeding requires: first, a thorough clinical evaluation; second, consideration of colonoscopic investigation; and third, documentation of this discussion.

Bleeding from a benign perianal origin is classically bright red, accompanies a bowel motion, is on the toilet paper, not mixed with the faeces and associated with perianal symptoms such as pain or a lump. Patients presenting with symptoms of proximal bleeding( ie, dark red bleeding), clots, painless bleeding, bleeding not accompanied by stool and the absence of local perianal symptoms, should be considered