COLON CANCER

• Definition• Signs & symptoms

• Treatment• Root of the disease

What is the colon? Colon or commonly known as the large bowel is made up of

the colon ascending, transverse, descending & sigmoid colon It is approximately 5 feet long and together with the rectum &

anus it is referred to as colorectal

Colorectal cancer (CRC) CRC is the third most common cancer in Canada but is the second

commonest cause of death from cancer in both men and women Around 423 Canadians are diagnosed with CRC each week

while 175 die each week from this disease During life time of a Canadian

One in 14 in men and one in 15 women is expected to develop CRC

Colon cancer has been found to be more common in women while in men, rectal cancer is more common

Age is considered as a major risk factor for the development of CRC The condition is rare before the age of 40 years but the risk

increases with age with a peak of incidence seen between the ages 60-70

Colorectal cancer (CRC) Staging of CRC provides a guide on the best treatment option

for that particular patient and also helps in to evaluate the prognosis.

Colorectal cancer (CRC) Several staging systems exist but most common ones are

TNM method - primary tumour (T), the status of regional lymph nodes (N), and the presence or absence of distant metastases (M) – used commonly

Dukes’ classification

Signs & symptoms CRC patients may present in three ways

Patient complaining of clinical features suggestive of CRC During screening of high risk patients Emergency admission from features of CRC e.g. – intestinal

obstruction Signs and symptoms of CRC is non specific in most of the

patients Early symptoms mimic variety of other diseases of the large

intestines Some patients may present initially with features of metastatic

disease (spread out of the colon) e.g. – enlarged liver, ascites

Signs & symptoms Some of the common presenting symptoms are as follows

Abdominal pain A change in the normal bowel habit e.g. – diarrhoea,

constipation or both Blood in stools Abdominal distension Weight loss Feeling of incomplete evacuation of bowel weakness

Physical findings may include: Abdominal lump Palpable mass, blood on digital rectal examination Metastatic features – enlarged liver, ascites

Signs & symptoms

Treatment Surgical resection of the tumour remains the best treatment

method for localised disease Type of surgery depends on the stage of the disease

Chemotherapy, immunotherapy (both given systemically), radiotherapy (local) Carried out for CRC which has spread beyond the colon

Surgery may sometime be combined with chemotherapy and radiotherapy or both modalities This can be done before the surgery or after the surgery Used to reduce the progression of disease after surgery and

to improve overall survival Sometimes used to reduce the size of the tumour before

surgery

Treatment

Root of the disease How does a cancer develop?

Normal cells in the body respond to various extracellular stimuli & these in turn activates genes that stimulate cell growth

Cancer arises when a normal cell, for variety of reasons escapes the normal restrictions placed on its growth and begins to divide in an abnormal fashion

These extracellular stimuli can be divided in to genetic and environmental

Root of the disease Colon cancer can be described as an multifactorial disease in

which more than one stimuli is responsible for the cause of the disease

Around 80% of cases are sporadic The following are considered as causes of colon cancer

Genetic factors (about 20% have an inheritable component) A family history of CRC, specially if a single first degree

relative is affected the risk is increased 2-3 folds while if 2 are affected the risk increases to 3-4 fold

People with polyps e.g. - familial adenomatous polyposis (FAP) has an almost 100% risk of developing colon cancer by age 40 years

People with a family history of other cancers e.g. – breast, uterine ovarian

Polyps

Root of the disease Environmental factors

Dieta lot of red meat and processed meats increases bowel

cancer risk (Poultry meat doesnt increase the risk). Alcohol Fiber containing diet (fruits, vegetables, cereals etc),

calcium and dairy has a protective effect Obesity (high BMI)

Inflammatory conditions of the colon e.g. Ulcerative colitis or Crohn;s disease

Colorectal cancer (CRC) Majority of CRC develops from a growth called polyps which

overtime may turn into a cancer Normal colonic epithelium changes into adenomatous

polyps which later transforms into invasive colorectal cancer

Previously mentioned stimuli are responsible for this transformation

Colorectal cancer (CRC)

References Cancer research UK. Bowel cancer Colon Cancer Canada. Fast facts on colorectal cancer Colorectal cancer: symptoms, diagnosis and treatment. Nationa

l Institute of Health magazine. 2009; Volume 4 Number 2

Merck Manuals Professional Edition. Colorectal cancer British Medical Journal (BMJ). Best practice Kumar and Clark's Clinical Medicine, 8th Edition