Colorectal Cancer Flashcards
Presenting features of colorectal cancer
-Change in bowel habits: Patients with colorectal cancer may experience a change in their bowel habits, such as constipation, diarrhoea, or alternating between the two. They may also feel the need to have a bowel movement more frequently than usual.
-Rectal bleeding: Blood in the stool or rectal bleeding is a common symptom of colorectal cancer. The blood may be bright red or melena.
-Abdominal pain and discomfort: Patients with colorectal cancer may experience abdominal pain, cramping, or discomfort. This may be due to the tumour obstructing the bowel or causing inflammation.
-Unexplained weight loss: Patients with colorectal cancer may experience unexplained weight loss, which can be a sign of advanced disease.
-Anaemia: Chronic bleeding from the tumour can lead to anaemia, which can cause fatigue, weakness, and shortness of breath.
-Bowel obstruction: In advanced cases, the tumour can completely obstruct the bowel, causing severe abdominal pain, nausea, and vomiting.
Location of colorectal cancer
rectal: 40%
sigmoid: 30%
descending colon: 5%
transverse colon: 10%
ascending colon and caecum: 15%
Risk factors for colorectal cancer
-Family history of bowel cancer
-Familial adenomatous polyposis (FAP)
-Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome
-Inflammatory bowel disease (Crohn’s or ulcerative colitis)
-Increased age
-Diet (high in red and processed meat and low in fibre)
-Obesity and sedentary lifestyle
-Smoking
-Alcohol
Colorectal cancer genetics
It is currently thought there are three types of colon cancer:
-sporadic (95%): series of genetic mutations (APC, K-ras, p53)
-hereditary non-polyposis colorectal carcinoma (HNPCC, 5%): Lynch syndrome, autosomal dominant, most common form of inherited colorectal C. Proximal colon, aggressive, MSH2, MLH1, endometrial cancer
-familial adenomatous polyposis (FAP, <1%): autosomal dominant, polyps, APC
Colorectal cancer screening
-FIT: Faecal Immunochemical Test screening to older adults
=every 2 years to all men and women aged 60 to 74 years in England, 50 to 74 years in Scotland. Patients aged over 74 years may request screening
Referral guidelines for colorectal cancer
-with an abdominal mass, or
-with a change in bowel habit, or
-with iron-deficiency anaemia, or
-aged 40 and over with unexplained weight loss and abdominal pain, or
-aged under 50 with rectal bleeding and either of the following unexplained symptoms:
=abdominal pain
=weight loss, or
-aged 50 and over with any of the following unexplained symptoms:
=rectal bleeding
=abdominal pain
=weight loss, or
-aged 60 and over with anaemia even in the absence of iron deficiency
Investigation of colorectal cancer
-Colonoscopy is the gold standard investigation. It involves an endoscopy to visualise the entire large bowel. Any suspicious lesions can be biopsied to get a histological diagnosis, or tattoo in preparation for surgery.
-Sigmoidoscopy involves an endoscopy of the rectum and sigmoid colon only. This may be used in cases where the only feature is rectal bleeding. There is the obvious risk of missing cancers in other parts of the colon.
-CT colonography is a CT scan with bowel prep and contrast to visualise the colon in more detail. This may be considered in patients less fit for a colonoscopy but it is less detailed and does not allow for a biopsy.
Staging of colorectal cancer
-carcinoembryonic antigen (CEA)
-CT of the chest, abdomen and pelvis
-their entire colon should have been evaluated with colonoscopy or CT colonography
-patients whose tumours lie below the peritoneal reflection should have their mesorectum evaluated with MRI.
Surgery in colorectal cancer
-Resection only cure
-Caecal, ascending or proximal transverse colon: right hemicolectomy: ileo-colic anastomosis
-Distal transverse, descending colon: left hemicolectomy: colo-colon
-Sigmoid: high anterior resection: colo-rectal
-Upper rectum: anterior resection (TME): colo-rectal
-Lo rectum: anterior resection (low TME): colo-rectal (+/- defunctioning stoma)
-Anal verge: abdomino-perineal excision of rectum
Overview of medical treatments for colorectal cancer
Chemotherapy
=Used in the neoadjuvant setting (particularly for rectal cancers), adjuvant setting, and for metastatic disease
=Common regimens include FOLFOX and FOLFIRI.
Radiation Therapy
=Predominantly used for rectal cancers in the neoadjuvant or adjuvant setting.
Targeted Therapies
=Bevacizumab (anti-VEGF) and Cetuximab (anti-EGFR), particularly for metastatic disease
Neoadjuvant treatment in colorectal cancer
-Rectal cancer ONLY
-Radiotherapy – reduces chance of local recurrence
=“Short course” – 5 days followed by surgery following week
=Chemoradiotherapy – 5 weeks of radiotherapy with chemotherapy
==Chemo sensitises tumour to radiotherapy (makes it more effective). Not a systemic dose.
==Wait to let it work (shrink the cancer and kill it) and then have surgery
Adjuvant chemotherapy
-All cancers
-Reduce risk of recurrence – kill micro-metastatic disease
-Based on risk factors on pathology – big tumours (T4), nodes involved, lympho vascular invasion, micro-satellite instability
-Balance of risks and benefits – see decision aid
-Options:
=5-FU – intravenous or oral pro-drug (capecitabine)
=Oxaliplatin and 5-FU
-Trials – Add Aspirin – adjuvant Aspirin
Palliative chemotherapy
-Not a cure
-Prognosis can vary hugely
-Decision –making depends on quality of life versus quantity:
=patient wishes
=fitness for treatment: cancer burden and symptoms, other co-morbidities (affect safety of treatment)
Systemic anti-cancer therapy options
-5-FU (or capecitabine)
-Raltitrexed
-Oxaliplatin and 5-FU
-Irinotecan ± 5-FU
-Targeted agents (given with chemotherapy)
=cetuximab – EGFR monoclonal antibody
=aflibercept – VEGF trap (anti-angiogenic)
=encorafenib (BRaf mutated tumours- often have poorer outcomes) &cetuximab
-Trifluridine/tipiracil (Lonsurf)
-Immunotherapy – microsatellite unstable tumours (Mismatch repair status done with immunohistochemistry) (may be Lynch syndrome so genetics important)
