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HOME | Frequently Asked Questions
Frequently Asked Questions
Summary
Colon cancer is an abnormal (or malignant) growth arising from the inner lining
(mucosa) of the large bowel. Like a person with many names, colon cancer can also
be called large bowel cancer or colorectal cancer. If left untreated, colon cancer can
grow larger and spreads through the wall to the outer surface of the bowel. It may
also spread via the blood stream or lymphatic system to other parts of the body.
Secondary growths may develop in distant organs, such as the liver or lung.
Colon cancer is one of the commonest cancers affecting both man and women.
In Hong Kong, it is the third commonest cancer and the third commonest cause of
cancer death. Every year, more than 2,000 Hong Kong people are found to have
colon cancer. People over 40 years of age are more likely to develop this cancer,
and the risk increases as we grow older. The average age of colon cancer sufferers
in Hong Kong is 60 years old.
The large bowel consists of two main parts : the colon and the rectum. Colon
is a muscular tube forming the last two metres of the body’s digestive system.
Rectum is the short tube leading down from the end of the colon to the back
passage.
What Causes Colon Cancer?
We don’t know for certain what causes colon cancer. Majority (80%) of colon
cancers are related to environmental causes particularly our diet. Some food may
help protect us from colon cancer, while others may help it develop. There is
growing evidence that a high fat and low fibre diet is related to colon cancer. On
the other hand, eating plenty of fruits, vegetables and produce high in fibre (such as
cereals, brown rice/bread) may help prevent colon cancer.
About 20% of colon cancer are related to heredity. People with close relative(s)
(parents, brothers, sisters or children) having colon cancer are more likely to
develop it. The level of risk depends on the number of close relatives with colon
cancer and their age of developing cancer.
What are the Symptoms of Colon Cancer?
Colon cancer may develop the following symptoms :
· Blood or mucus (or both) in the bowel movements
· Unexplained changes in bowel habits lasting more than two weeks, such as
constipation or diarrhoea or both
· Persistent “colicky pain” in the abdomen
· Tiredness or paleness from anaemia
Sometimes, symptoms appear only after the colon cancer has spread.
On the other hand, in many cases these symptoms do not mean cancer, but tests
may be needed to make sure. The older you are, the more likely that the symptoms
could mean cancer.
What are Polyps?
Polyps are mushroom-shaped growths on the inner lining of the large bowel.
Although they are non-cancerous, one type of polyp called adenoma is the
precursor of colon cancer. If untreated, some adenoma will grow bigger and
become cancerous in a number of years.
Polyposis is a hereditary condition in which an individual develops hundreds of
polyps in the large bowel. For more information, please go to the section on FAP.
Who is Most At-Risk?
For an average person, the risk of colon cancer increases with age from 50
years onwards. Individuals having close relatives with colon cancer are at-risk. The
risk increases with increasing number of affected close relatives. A person with a
history of large or numerous colonic adenoma or a history of extensive ulcerative
colitis for more than ten years are also at risk of colon cancer.
Those most at-risk are individuals with hereditary colon cancer syndromes
caused by abnormal change (mutation) of known genes. This includes : polyposis
syndrome which is a rare but easily recognizable condition; non-polyposis
syndrome which has no easily recognizable features except a strong family history
of colon cancer. Genetic testing is helpful in pinpointing this condition.
Who should have a check-up?
Studies have shown that regular check-up (screening) is the most effective way to
prevent colon cancer. Whether you are at-risk of colon cancer or not, regular
screening is your best bet against this very common cancer.
I am over 50 – Should I have a check up?
Even if you have no risk factor for colon cancer, we recommend you to have regular
check-up from age 50 onwards. The World Health Organization (WHO) recommends
the following scheme to you :
· Stool test for occult blood annually; and
· Telescopic examination of the lower part of colon (called sigmoidoscopy) every 3
to 5 years.
If you have a family history of colon cancer, your check-up may have to start earlier,
say from age 40 or earlier. Instead of stool test and sigmoidoscopy, you may need a
complete telescopic examination of the whole colon (called colonoscopy).
I would like to have a check up – how do I start?
If you live in Hong Kong, stool test can be arranged through the Hong Kong Crusade
Angels (telephone and address provided). If your family history fits in our Registry’s
recruitment criteria (click to recruitment criteria), you can contact us for check-up
arrangement.
If you live elsewhere, you can contact your local cancer registry for check-up
information and arrangement. This site has a list of registries around the world.
Chinese FAQ
甚麼是結直腸癌?
結直腸癌是一種發生於大腸內壁(粘膜)的異常(惡性)增生，又被稱為大腸癌或結腸癌。如果不予治療，結直腸癌能夠體積增大且穿透腸壁至大腸外表層，它也可通過血道和淋巴道轉移至身體的其他部位。繼發轉移可以發生於肝臟及肺等遠隔臟器。
結直腸癌是發生於男性與女性的其中一種最常見的癌症。在香港，它是第二大高發癌，死亡率在所有癌症中佔第三位。每年約2400例結直腸癌在香港被發現。40歲以上的人容易患此癌，患病風險隨年齡而遞增。在香港，結直腸癌的平均發病年齡為60歲。
大腸主要包括兩部份：結腸和直腸。結腸是構成人體消化系統末端兩米的肌肉管道。直腸是連接結腸末端與肛門的短管。
結直腸癌的病因是甚麼？
結直腸癌的具體病因尚不清楚，大部份﹝80%﹞結直腸癌與環境因素有關，特別是飲食因素，一些食物可以保護我們免得結直腸癌，而另一些食物卻有導致結直腸癌發生的作用。越來越多的證據表明高脂低纖維食物與結直腸癌的發生有關。相反，大量的水果、蔬菜及高纖維食物將有助於防止結直腸癌的發生。
大約20%的結直腸癌與遺傳有關。有患結直腸癌的親屬﹝父母、兄弟、姐妹或子女﹞的人更易患此病，其患病危險性與患結直腸癌的近親數及他們的發病年齡有關。
結直腸癌的症狀是甚麼?
結直腸癌將有以下症狀：
??排便中可見血或/及粘膜
??持續兩周以上的難以解釋的排便習慣的改變
??持續的腹部疼痛
??蒼白、乏力等貧血症狀
有時，症狀出現於結直腸癌播散之後。
許多情況下這些症狀並不意味著癌症，而需要實驗室檢查來進一步確診，患者的年齡越大， 這些症狀就越可能表示癌症的發生。
甚麼是息肉?
息肉是生長於大腸內表面的蘑菇樣物體，盡管它們不是惡性的，但其中一種被稱為腺瘤的息肉卻是結直腸癌的前身， 如果不予治療，一些腺瘤將會增大且在幾年內惡變。
息肉病是一種遺傳性疾病。患病者的大腸內生長有數以百計的息肉。關於此病的更多信息，詳見 家族性結直腸腺瘤息肉綜合症章節。
誰是高危人群?
對於普通人而言，結直腸癌的發病危險從50歲開始隨年齡而遞增，近親患有結直腸癌者具有較高結直腸癌發病危險。此危險隨患結直腸癌近親數的增加而增加。另外，具有大的或數量多的結直腸腺瘤或具有10年以上廣泛性潰瘍性結腸炎病史的患者也有患結直腸癌的傾向。
結直腸癌的高危人群是患有由已知基因的異常改變﹝突變﹞導致的遺傳性結直腸癌綜合症的人群， 這些疾病包括少見但易於識別的息肉病綜合症及除非有明顯結直腸癌家族史否則難以識別的非息肉性綜合症。遺傳學診斷有助於識別這些疾病。
誰應接受結直腸癌篩查?
研究顯示定期篩查是預防結直腸癌的最有效的方法。無論你是否有結直腸癌的發病危險，定期篩 查是你對付這個高發癌症的最好策略。
我已年過50 - 我應當接受檢查嗎?
即使您 沒有結直腸癌的高發因素，我們仍建議您從50歲起接受定期檢查。世界衛生組織(WHO)為您提出如下建議：
??每年做一次大便潛血試驗
??每3到5年做一次末段結直腸的內窺鏡檢查﹝乙狀結腸鏡檢查﹞
如果您有結直腸癌的家族史，您應當提早接受檢查，從40歲或更早開始您可能需要接受結直腸全長的內窺鏡檢查﹝大腸鏡檢查﹞而不是大便檢查和乙狀結腸鏡檢查。
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