Diagnosis and investigations
How to Treat – Bowel cancer part 1 : Diagnosis
from previous page ing Program ( NBCSP ).
While the NBCSP provides an element of protection for Australian society , three significant limitations exist : the program will not be completely rolled out until at least 2020 ; uptake of the program remains modest ; and in addition , community-based FOBT is ideally suited to those regarded as being of ‘ average risk ’. It is thus incumbent on all GPs to risk stratify all their adult patients and provide them with advice regarding screening for large bowel cancer .
Colorectal cancer ( CRC ) arises from the epithelial cells of the lining of the colon and rectum , and generally manifests as an adenocarcinoma , although there are other recognised variants that may be associated with a specific genetic predisposition .
In most cases , the specific pathogenesis of large bowel cancer is multifactorial and a number of risk factors have been identified , including diet , age , living in Western civilisation , family history and lifestyle factors ( discussed later ), which play a lesser but nonetheless important role . Advanced and metastatic colorectal cancer is often chemo-sensitive and many of the significant advances in the management of bowel cancer of the past 20 years relate to improved responsiveness to chemotherapy .
Figure 1 and 2 . Cancer of the large bowel .
Diagnosis and investigations
WHILE certain symptoms ( see box ) may be suggestive of the presence of a cancer , they are also common in the community , and are frequently presenting complaints for a variety of often benign and innocuous conditions . Thus , GPs need to have a functional framework for evaluating patients who present with any of these symptoms in order to assess whether further investigation is required .
The patient with rectal bleeding Rectal bleeding is a common presentation to GPs . The vast majority of cases with rectal bleeding are due to benign perianal causes . However , as colorectal cancer is a common condition in Australia and can affect adults of any age , any adult patient who presents with rectal bleeding requires first , thorough clinical evaluation , second , consideration of colonoscopic investigation , and finally , documentation of the discussion .
Classically , bleeding from a benign perianal origin will be bright , on the toilet paper or in the bowl , not mixed with the faeces , and often associated with local perianal symptoms , such as the presence of a lump or local pain , possibly suggestive of a fissure .
Whenever adult patients present with rectal bleeding at any age , they should initially be evaluated for symptoms suggestive of proximal pathology within the large bowel . Physical examination should include a rectal examination to ascertain whether perianal pathology is present or not . The need or otherwise for further investigation can then be tailored to the individual circumstances of that patient .
If , for example , a patient in their early 20s with a negative family history for colorectal neoplasia presents with bright bleeding suggesting perianal origin , no symptoms of proximal pathology and rectal examination reveals haemorrhoids , then the subsequent yield from colonoscopy would be very low indeed .
Conversely , if an older patient in their 60s presents with dark altered blood in the faeces with associated change in bowel habit , weight loss and abdominal discomfort lasting weeks , then almost certainly colonoscopy will be indicated .
Symptoms of large bowel cancer or other significant large bowel pathology
Persistent and unusual change in bowel habit lasting more than two weeks
Blood in the faeces
Persistent or unusual abdominal pain
Weight loss and anorexia Symptoms of anaemia
Risks of colonoscopy
Risk of perforation of the large bowel , approximately one in 1500
If perforation occurs , there is a significant likelihood of requiring abdominal surgery +/ - stoma formation
Risk of bleeding after removal of polyps or biopsies ~ 1 %, depending on size of polyp
General risks of anaesthesia
After a thorough evaluation of symptoms and physical examination , a discussion with the patient should occur including an evaluation of the likelihood of the bleeding being anything other than perianal in origin , the option of colonoscopic screening , and a balanced discussion of the risks and benefits of colonoscopy .
Not every patient with rectal bleeding requires colonoscopy . However , in any adult patient with bleeding , the option of colonoscopy needs to be discussed , and the context and outcome of that discussion clearly documented for medicolegal purposes . Specific case discussions relating the decision to proceed or otherwise with colonoscopy can be found in the online resources .
Screening in the asymptomatic population The NHMRC has issued guidelines for stratification for risk in the Australian population , and these are listed in table 1 .
The vast majority of Australians , around 95 %, fulfil NHMRC category one . These are patients of average risk , who are asymptomatic and have a negative or weak family history of colorectal cancer or polyps . These are the patients for whom the NBCSP is tailored . The indicated investigation for these patients is annual or biennial
Table 1 . NHMRC guidelines for colorectal cancer screening in asymptomatic patients Category
Category one — those at or slightly above average risk ( covers about 95 % of the population )
Category two — those at moderately increased risk ( covers 1-2 % of the population )
Category three — those at potentially high risk ( covers less than 1 % of the population )
Source : NHMRC .
FOBT starting at age 50 until the age of 74 . In the current NBCSP , adult patients are sent an FOBT in the mail at age 50 .
Under current arrangements in 2017 , repeat testing is performed every five years in some age groups , although with the complete rollout of the program in 2020 , the kits
Features
Asymptomatic people fit into this category if there is :
• No personal history of colorectal cancer ( CRC ) or ulcerative colitis and no confirmed family history of colorectal cancer or
• One first-degree ( parent , sibling , child ) or second-degree ( aunt , uncle , niece , nephew , grandparent , grandchild ) relative with CRC diagnosed at age 55 or over
Screening guidelines
• FOBT at least every two years from the age of 50
• Consider sigmoidoscopy ( preferably flexible ) every five years from the age of 50
• It is important to advise individuals to see their doctor if they develop symptoms of CRC
Asymptomatic people fit into this category if there is :
• One first-degree relative with CRC diagnosed before the age of 55 or
• Two first- or second-degree relatives on the same side of the family with CRC diagnosed at any age
Screening guidelines
• Offer colonoscopy every five years starting at 50 or at an age 10 years younger than the age of CRC in the family , whichever comes first
• Sigmoidoscopy plus double contrast barium enema is an acceptable alternative to colonoscopy if colonoscopy is unavailable
• Consider FOBT in intervening years
• Colonoscopic follow-up ( or sigmoidoscopy plus double contrast barium enema ) is necessary for those with a positive FOBT
Asymptomatic people fit into this category if there are :
• Three or more first- or second-degree relatives on the same side of the family diagnosed with CRC — suspected hereditary non-polyposis colon cancer ( HNPCC ) or
• Two or more first- or second-degree relatives on the same side of the family diagnosed with CRC , including any of the high-risk features : – Multiple CRC in one person – CRC before the age of 50 – At least one relative with endometrial or ovarian cancer ( suspected HNPCC ) or – At least one-first degree or second-degree relative with CRC , with a large number of adenomas throughout the large bowel — suspected familial adenomatous polyposis ( FAP ) or – Someone in the family in whom the presence of a high-risk mutation in the adenomatous polyposis coli or one of the mismatch repair genes has been identified
Screening guidelines
• These high-risk families should be managed with the support of clinical genetics and cancer genetic services , underpinned by family registries
• Screening of at risk members of proven HNPCC families should be by annual or two-yearly colonoscopy , commencing around the age of 25
• Annual screening should be offered to individuals carrying a germline mutation
will be offered biennially .
Current community uptake of FOBT when offered under the NBCSP is disappointingly modest , at about 35 %. There is strong evidence to suggest that support , validation and confirmation of this program by GPs would improve uptake .
It is thus important that all patients over 50 have a clear documented discussion regarding whether they are appropriate for inclusion in the NBCSP , whether they have performed the test sent to them , the importance of screening and assessment for symptoms . cont ’ d page 20
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