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COLORECTAL CANCER Introduction June is Bowel Cancer Awareness Month, during which Bowel Cancer Australia aims to raise awareness and funds dedicated to the prevention and early diagnosis of Australia’s second deadliest cancer, research into the disease, and quality treatment and best care for people diagnosed with it. Pharmacists and pharmacy support staff are ideally placed to help with these important messages. Colorectal cancer is estimated to be the second most commonly diagnosed type of cancer in Australia and the second leading cause of cancer death.1 The mainstay of treatment is surgical resection. But often radiotherapy, chemotherapy and monoclonal antibody therapy are necessary, depending on staging and location of the disease.2 Those of advancing age are a major risk group3 and these individuals are likely to have other chronic diseases and be a familiar face in your pharmacy. Community pharmacists should have basic knowledge of colorectal cancer symptoms, treatment, adverse effects, screening and monitoring, to assist patients and their families facing the long, arduous treatment regimens planned. Epidemiology Overall cancer incidence in Australia increased from 47,462 cases in 1982 to 131,452 cases in 2015. It was estimated that almost 16,000 Australians would be diagnosed with colorectal cancer in 2020 and more than 5500 would die of the disease in the same year.4 Overall colon and rectal cancer rates in people aged under 50 years have increased. The colon cancer incidence rate increased by up to 9.3 per cent a year from the mid-2000s, while rectal cancer incidence rates have risen by up to 7.1 per cent a year since the early 1990s. However, colon and rectal cancer rates decreased in people aged 50 years and over, likely due to bowel cancer screening in this age group.5 Risk factors Genetic risk factors Genes have been identified which, when inherited in a mutated form, substantially increase an individual’s risk of developing colorectal cancer. The best studied of these genes include the DNA mismatch repair genes MLH1, MSH2, MSH6 and PMS2 (Lynch syndrome); the APC gene (familial adenomatous polyposis); and MUTYH (MUTYH-associated polyposis). Mutations in these genes cause fewer than five per cent of all colorectal cancer cases and, at most, explain only half the reasons why family history is a risk factor for this disease. These patients are often under a high level of surveillance from secondary or tertiary healthcare facilities.6 The remainder of the observed increases in familial risk could be due in part to mutations in yet to be discovered colorectal cancer susceptibility genes, polygenic factors such as single-nucleotide polymorphisms, or dietary and other lifestyle factors shared by family members.6 Age Age is a major risk factor for colorectal cancer (Figure 1).7 Lifestyle Lifestyle factors such as obesity and the consumption of red and processed meat are associated with a small and/or uncertain increased risk of colorectal cancer. Although many of these associations have been seen consistently in observational studies, the causal relationship of these associations is largely unproven.8 Clinical presentation Clinical symptoms of colorectal cancer are outlined in Box 1.9 Among symptomatic patients, clinical manifestations also differ depending on the location of the cancer as highlighted below. • A change in bowel habits is a more common presenting symptom for left- sided than right-sided colorectal cancers. • Melaena (blackened tarry stools) is more often caused by rectosigmoid colorectal cancers than right-sided colon cancer. • Iron deficiency anaemia from unrecognised blood loss is more common with right-sided colorectal cancers. • Caecum and ascending colon cancers have a fourfold higher mean daily blood loss than cancers at other colonic sites. • Abdominal pain can occur with cancers arising at all sites. It can be caused by a partial obstruction, peritoneal dissemination, or intestinal perforation leading to peritonitis. • Rectal cancer can cause tenesmus (feeling of need to have a bowel movement TO PAGE 50 Figure 1. Prevalence of colorectal cancer per 100,000 population and population age RETAIL PHARMACY • JUN 2021 CPD ACTIVITY 49 2 CPD CREDITS Jo Comper, B Pharm (Hons) M Pharm Jo is an accredited pharmacist performing HMRs in her home town, Cairns, and in outback Australia. She undertook basic training in the UK’s National Health Service and completed a master’s degree at the University of Nottingham. She now carries out freelance work for various organisations and universities, developing continuing professional development articles and lecture series. LEARNING OBJECTIVES After completing this CPD activity, pharmacists should be able to: • Recognise common symptoms associated with colorectal cancer. • Describe treatments offered to patients with colorectal cancer. • State the bowel cancer screening process for average-risk individuals in Australia. • Identify prominent side effects associated with chemotherapy and monoclonal antibodies used to treat colorectal cancer. 2016 Competency Standards: 3.2, 3.6. Accreditation Number: A2106RP2 (exp: 31/05/2023).