CANCER MANAGEMENT
70 CANCER CONTROL 2014
found in red blood cells. iFOBT is not subject to false-negative
results in the presence of high-dose vitamin C supplements
and no dietary restriction is required because dietary
constituents such as red meat, cruciferous vegetables and
fruits do not affect the test. Since globin is degraded by
digestive enzymes in the upper gastrointestinal tract, iFOBT
is more specific for lower gastrointestinal bleeding and not
affected by bleeding from stomach, thus improving their
specificity to detect CRC and polyps. Hence, it is easier to
use iFOBT rather than cFOBT. Since FOBT may not detect a
tumour that is not bleeding, multiple stool samples should
be tested. The probability of CRC is clearly higher in
patients with positive rather than negative findings on
FOBT testing.
10 It is also suggested that iFOBT is more
sensitive than cFOBT in detecting early stage CRC
10
, and if
the results are positive for hidden blood, a colonoscopy is
required to investigate further. In order to be beneficial, the
test must be repeated approximately every 2 years.
The role of PC in promoting CRC screening
programmes
PC practitioners and health workers are ideally positioned to
improve participation of subjects in CRC screening
programmes with FOBT screening. Since a large number of
people above the age of 50 years interact with primary care
for routine health care, FOBT screening may be carried out
during these visits. All national organized screening
programmes initiate screening at age 50, as symptoms of
CRC may not be evident until late in the disease process.
A pilot CRC screening programme using iFOBT was
implemented through 154 primary care units and 12
community hospitals, at the PC level of Government Health
Services, in Lampang Province, to research the acceptability,
feasibility and scaling-up of screening in Thailand.13 A target
population 127,301 people aged 50-65 years were informed
about and invited to undergo CRC screening by community
health workers (HWs). The HWs provided the faecal sample
collection kits and explained how to use them and
participants brought their samples either to one of the
primary health units or community hospitals where nurses
performed iFOBT. Of the 127,301 target population, 80,012
(62.9%) were screened using iFOBT and 873 (1.1%) were
found positive and were referred to undergo colonoscopy at
the Lampang Cancer Hospital and endoscopic
polypectomy/biopsies were performed according to
colonoscopic findings. Of the 627 (72.0%) iFOBT-positive
persons who underwent colonoscopy, 23 were diagnosed
with CRC, 75 with advanced adenoma and 112 with nonadvanced adenoma.13
The stage-distribution of the detected
invasive cancers was as follows: 2 stage I, 12 stage II, 7 stage
III and 2 missing stage information. Those with confirmed
CRC received appropriate treatment. The successful
implementation of the pilot CRC screening with satisfactory
process measures indicates the feasibility of scaling up
organized CRC screening through PHC services in Thailand.
Primary prevention of CRC
There is compelling data regarding an inverse relationship of
physical exercise and risk of CRC. A meta-analysis of 52
studies found an overall relative risk (RR) of 0.76 (95%
confidence interval (CI): 0.72, 0.81) for CRC associated with
physical activity.14 The most motivating means of getting
patients to exercise regularly is to speak with them about
what activities they enjoy, or enjoyed in the past, focusing on
deriving pleasure from the activity. A vast amount of
information exists regarding the role of diets and dietary
components in relation to development of CRC, which
indicates that diets high in trans-fatty acids and saturated fat,
sugar and refined starches and low in fruits and vegetables
are associated with a higher risk of CRC.15
Advising people interacting with PC on being physically
active for at least 30 minutes, at least five days a week, on
maintaining a healthy weight, avoiding tobacco use in any
form, drinking no more than one drink a day for women or
two drinks a day for men and eating a diet rich in fruits,
vegetables and whole grains and less in red and processed
meat can be conducive to reducing the risk of CRC. Many of
the recommendations regarding diet, exercise and
normalization of weight will have ramifications far beyond
prevention of CRC and must be implemented as part of an
overall healthy lifestyles initiative.
Conclusion
Early detection of CRC at the PC level heavily relies on
symptoms, medical history, physical examination, clinical
There is increasing emphasis on
involving PC in the control of chronic
diseases, including cancer, as part of
the new integrated noncommunicable disease (NCD)
control
policy evolved by WHO