Dr Winson Tan from the Department of General Surgery (Colorectal Surgery) at Sengkang Health answers some commonly asked questions on colorectal cancer.
Colorectal cancer is the Number 1 cancer is Singapore.
The life time risk of an individual developing colorectal cancer in Singapore is estimated to be within the range of 3-4%.i
As Singapore has made tremendous economic progress over the past decades and attained the status of a developed economy, it is surprising that
a majority of colorectal cancers are still diagnosed at an advanced stage.
Clearly, we can do more to combat the number 1 cancer in Singapore.
An important element in our quest against colorectal cancer lies in patient education. Here, we attempt to answer several questions that are commonly asked by our patients.
Frequently asked questions about colorectal cancer
1) Can we prevent colorectal cancer?
Prevention of colorectal cancer is definitely possible as a majority (>80%) of cancer cases develop from pre-cancerous colonic polyps.ii
Removal of these pre-cancerous colonic polyps has been shown in studies to reduce the incidence of colorectal cancer by up to 80%.iii
Thus, colonoscopy screening, with removal of pre-malignant polyps at the same setting, offers the most effective means of preventing colorectal cancer.
Other measures which can help minimize your risk of developing colorectal cancer include:
- moderation of alcohol consumption,
- quitting smoking,
- regular physical activity (exercise) and
- a diet that includes adequate fruits and vegetables.
2) Colonic polyps: are they all the same?
There are many different types of colonic polyps. While not all of them may lead to cancer, the majority of colonic polyps discovered carry a risk of malignant transformation (adenomatous polyps).
The risk of cancer developing from adenomatous polyps also varies according to factors such as:
- the size of the polyp and
- the extent of abnormality on microscopic examination (degree of differentiation).
3) My relative has colorectal cancer. What is my risk?
There are multiple factors that need to be considered when assessing your risk of developing colorectal cancer based on family history.
In general, your risk of developing colorectal cancer depends on:
- the number of family members who have colorectal cancer,
- whether family members who have colorectal cancer are first degree relatives (parents, siblings or child) and
- the age your relatives were diagnosed with colorectal cancer.
As a crude estimation, those with one first degree relative with colorectal cancer carry a 2-fold higher risk of developing colorectal cancer while those with 2 or more relatives carry at 4-fold higher risk of developing colorectal cancer.iv
4) Is chemotherapy needed for all cases of colorectal cancer after surgery?
It is important to understand that the main treatment for curable colorectal cancer is surgery.
Chemotherapy’s role is mainly to augment the surgical treatment so as to reduce the likelihood of cancer recurrence.
Thus, chemotherapy is usually recommended for patients with cancers that are deemed to be at higher risk of recurrence.
These are usually patients with cancers that have involved the lymph nodes (stage III cancer). An oncologist may also recommend chemotherapy in certain patients with stage II cancers that exhibit features which put them at an increased risk of recurrence.
i. Information Paper on Colorectal Cancer. National Registry of Diseases Office. Singapore: Ministry of Health 2011.
ii. N Engl J Med 2016; 374:1065-1075 Colorectal Adenomas. Williamson B. Strum
iii. N Engl J Med. 1993 Dec 30;329(27):1977-81.Prevention of colorectal cancer by colonoscopic polypectomy. The National Polyp Study Workgroup. Winawer SJ1, Zauber AG, Ho MN, O'Brien MJ, Gottlieb LS, Sternberg SS, Waye JD, Schapiro M, Bond JH, Panish JF, et al.
iv. Butterworth AS, Higgins JP, Pharoah P. Relative and absolute risk of colorectal cancer for individuals with a family history: a meta-analysis. Eur J Cancer 2006;42:216–27