CANCER MANAGEMENT
68 CANCER CONTROL 2014
There is increasing emphasis on involving PC in the control
of chronic diseases, including cancer, as part of the new
integrated non-communicable disease (NCD) control policy
evolved by WHO. PHCs in more and more low- to middleincome countries are currently being equipped with essential
medications to control diabetes, hypertension, dyslipidemia,
chronic respiratory illness and facilities for the early
detection of cervical cancer by visual screening. However,
cancer is a heterogeneous disease involving several organs
and controlling cancer requires a multipronged approach
involving several stakeholders. We discuss the global role of
primary care practitioners in contributing to the early
detection and prevention of colorectal cancer (CRC) within
the context of integrating cancer control in primary care. CRC
accounts for 1,360,602 cases and 693,881 deaths globally;
347,395 cases and 198,242 deaths in developing countries
and the risk is steadily increasing in many developing
countries.5-7
Clinical suspicion of CRC in PC
Early detection of cancer is about finding it early when there
is a better chance of cure. The PC practitioner's awareness of
symptoms and signs of cancer, referral pathways and skills in
providing a cancer-related physical examination, taking
advantage of the opportunities provided by clients'
interaction in PC, are critical to trigger referral to secondary
or tertiary care for early diagnosis and treatment.
Identification of the symptoms and signs of cancer form the
core of the competency required for urgent referral of
patients suspected of having cancer. This could be
challenging, given the fact the symptoms are not specific to
many cancers and the evidence linking certain symptoms to
particular cancers is rather weak. Since the diagnosis of
cancer is relatively rare for PC practitioners, they need to sort
out the minority of patients who need urgent referral from
the majority who are unlikely to have the disease. They
should also take into account the harm associated with a
false-positive referral. This means that the PC practitioners
need in-service training and re-orientation for the clinical
suspicion of cancer and facilitating early diagnosis. These
"skills-building" exercises for PC personnel are often
overlooked and less emphasized when introducing cancer
early detection initiatives in primary care, particularly in lowand middle-income countries.
Awareness about people at increased risk of CRC such as
being over 50 years old, complaining of rectal bleeding,
having recent changes in bowel habits, a personal history or
family history of colorectal polyps and CRC and a family
history of hereditary CRC syndromes, familial adenomatous
polyposis (FAP) or hereditary non-polyposis colon cancer
(HNPCC), and patients with inflammatory bowel disease
(IBD), such as ulcerative colitis and Crohn's disease, is
conducive to early detection. Since more than 90% of CRCs
occur in those aged over 50, ageing is considered the major
risk factor in people without IBD. For patients with a family
history of CRC in a first-degree relative, especially with a
relative diagnosed before age 55, the risk of CRC is nearly
double that of patients without a family history.
The symptoms associated with CRC are given in Table 1.
Patients presenting with rectal bleeding or change in bowel
habits are more likely to be referred by PC practitioners for
specialist consultation, sigmoidoscopy or colonoscopy.
8-10
More often than not, these symptoms may be caused by
conditions other than CRC such as gastrointestinal infection,
haemorrhoids, irritable bowel syndrome or inflammatory
bowel disease. As many patients presenting in PC present
with abdominal symptoms, it is important that PC
practitioners can identify those at increased risk of CRC, yet
they may not encounter more than one or two CRC patients
in a year. It is often suggested that symptoms persisting for
more than 6 weeks should trigger prompt referral for
diagnostic investigations that include specialist consultation
and endoscopy. Among the symptoms, rectal bleeding, dark
stools or blood in the stools and changes in bowel habits are
the most common and well-recognized alarm symptoms for
CRC with a high predictive value for cancer.
8-12 Positive
predictive value indicates the probability of diagnosis of the
condition when one has the symptom.
In a cohort study involving 762,325 patients aged 15 years
or above, registered with 128 United Kingdom general
practices between 1994 and 2000, a first occurrence of rectal
bleeding, with no previous cancer diagnosis, occurred in
15,289 (2.0%) patients and 338 were diagnosed with CRC in
the following three years, yielding a positive predictive value
of 2.2%; the predictive value increased significantly with
increasing age (Table 2).9 Rectal bleeding was associated with
a higher risk of CRC diagnosis within 90 days immediately
after presentation: 257 of 338 (76%) of diagnosed CRC
Since more than 90% of CRCs occur
in those aged over 50, ageing is
considered the major risk factor in
people without IBD