Colon Cancer

Colon cancer is a malignant tumour involving the large intestines. It is one of the more common cancers in our society. The commonest type of colon cancer are adenocarcinomas (95%) with the remaining 5% comprising of mesenchymal tumours (GIST), neuroendocrine tumours, lymphomas and sarcomas.

Surgical specimen of colon cancer with polyps

The risk factors include:
- older age
- diet high in fat and low in fibre
- hereditary (20% of cases including Familial Adenomatous Polyposis & Hereditary Non-Polyposis Colon Cancer)
- male sex
- patients with inflammatory bowel disease (especially ulcerative colitis)
- colonic polyps
- obesity
- cigarette smoking
- acromegaly
- patients with an uretero-sigmoidostomy

Patients usually present with:
- altered bowel habits: constipation alternating with bouts of foul smelling watery stools
- bloody stools
- mucous in the stools
- loss of weight and loss of appetite
- incidental finding on screening colonoscopy
- symptoms of metastasis (malignant spread) eg difficulty breathing, liver swelling, abdominal distension, bone pain, confusion, weakness

Patients can also present as an emergency case with:
- intestinal obstruction with or without abdominal distension
- perforation of the large intestines
- symptoms of anaemia due to profuse bleeding from the tumour

Investigations include:
- colonoscopy which can visualise and biopsy the tumour
- CT-scan to look for spread (metastasis) of the tumour to the lungs, liver or lymph nodes
- serum CEA levels (tumour marker for colon cancer): raised CEA reinforces the diagnosis and can be used for surveillance to detect recurrence
- genetic testing for hereditary colon cancers eg APC, hMLH1, hMSH2, hPMS1 genes

Colonoscopy image of colon cancer

Management of patients with colon cancer will depend on the stage and extent of the disease. The mainstay of treatment for colon cancer is surgery. The type of surgery will depend on the site of the cancer. A right hemicolectomy is done for cancers at the right side of the colon. Left hemicolectomy for cancers of the left colon, anterior resection for cancers of the sigmoid and rectum.

Patients with advanced stage 2 and stage 3 colon cancers will require chemotherapy after surgery. Common chemotherapy regimes used include 5-FluoroUracil, Oxaliplatin and Irinotecan. Radiotherapy is indicated when surgical margins are involved. Newer treatment options include the use of molecular targeted therapy such as bevacizumab and cetuximab.   
Patients who present with metastatic disease (stage 4) will usually be treated with palliative and supportive care. However, recent advances have shown that resection of metastatic liver and lung lesions improves patient survival.

Breast Cancer

Breast cancer is the commonest cancer in women all over the world. The incidence is highest in women around the age of 40 - 60 years but it may also occur at any age. The lifetime risk of developing a breast cancer in a woman is 11%.

Patients with breast cancer commonly present with:
- breast lump
- retracted nipple
- lymph node swelling in the axilla (armpits)
- ulcerated swelling on the breast
- redness & inflammation of the breast
- nipple discharge which can be blood or mucous
- incidental finding on screening by mammogram

95% of breast cancer occur sporadically while only 5% are due to genetic factors. The genes which are implicated in breast cancer are BRCA-1 and BRCA-2. Patients with BRCA genes have a 50% lifetime risk of breast cancer and a 30% risk of getting a breast cancer on the opposite breast. Women with BRCA-1 also have a 30% risk of getting ovarian cancer.

Other genetic syndromes associated with breast cancer are:
- Li Fraumeni syndrome which includes brain tumours, sarcomas and leukaemias
- Cowden syndrome which includes thyroid tumours and skin lesions
- Peutz-Jaghers syndrome which includes gastro-intestinal tract polyps, pigmentation of the lips and increased risk of gastro-intestinal cancers.

To confirm the diagnosis of breast cancer, 'Triple Assesment' is recommended. This includes:
- breast examination by the doctor
- tissue biopsy with Fine Needle Aspiration Cytology (FNAC) or Core Biopsy
- radiological investigations with a Mammogram or Ultrasound or MRI

Mammogram

Patients with strong family history of breast cancer should undergo genetic testing for BRCA-1 and BRCA-2 genes.

Once the diagnosis of breast cancer is confirmed, a patient is counselled on her diagnosis and the plan of management. The management will depend on the stage of the cancer, type of cancer (DCIS vs Invasive Ductal/Lobular Cancer) and patient's Estrogen/Progestrone Receptor (ER/PR) status.

For patients with non-metastatic (have not spread beyond the breast) cancer, the initial treatment is mastectomy (breast removing surgery) with removal of lymph nodes. The indications for mastectomy are:
- Invasive breast cancer more than 3cm
- multifocal DCIS
- patients with recurrent cancer after breast conserving surgery
- young patients who have a high risk of cancer recurrence (BRCA carriers)
- old patients who do not want to undergo further surgery
- male patients with breast cancer

Patients with DCIS (ductal carcinoma in situ) or Invasive breast cancer less than 3cm can undergo Breast Conserving Surgery (BCS) with post-operative radiotherapy. However, there is a 10% chance that further surgery might be required with BCS.

Removal of lymph node is needed for control of loco-regional disease and for more accurate staging of the disease. A few techniques commonly used are lymph node dissection or sampling or Sentinel Lymph Node Biopsy.

Post mastectomy, if the patient has got lymph node involvement or the tumour is bigger than 1.5cm, it is necessary for the patient to undergo chemotherapy which will further destroy the cancer cells in the body. The common regime used is a combination of 5-FluoroUracil, Epirubicin and Cyclophosphamide.

Patients who have ER/PR positive should be started on Tamoxifen tablets (20mg daily) which will reduce the level of estrogen in the body and reduce the risk of recurrence of the cancer. Post menopausal patients can be started on aromatase inhibitors such as anastrozole or letrozole which also reduces estrogen levels.

Patients who are HER-2 (human epidermal growth factor receptor-2) positive can be started on trastuzumab which is shown to improve disease  free survival. However, this drug is contraindicated in women with heart failure.

Patients with locally advanced breast cancer (size more than 5cm or with involvement of chest wall or skin) should undergo pre-operative chemotherapy to reduce the size of the cancer. The regime is the same as the post-operative one or a taxane based (docetaxel) chemotherapy can also be used.

Post-mastectomy, patients who are keen for reconstruction of their breast should be referred to a Plastic Surgeon for reconstructive surgery. The breast can be reconstructed with the patients own muscles and skin (free or pedicled flap reconstruction) or with a prosthetic breast implant.

What is a Cancer?

A Cancer is defined as an abnormal mass of tissue, growth of which is uncoordinated and exceeds that of normal tissue which persists even after cessation of the stimuli which provoked it. The main hallmarks of cancer are that it is purposeless, it preys on its host and it is autonomous.

The biology of Cancer growth are:
- Self sustained growth signals
- Insensitivity to inhibitory growth signals: Normal cells respond tumour suppressor genes.
- Limitless growth potential: It does not stop growing unlike normal cells.
- Evasion of apoptosis (programmed cell death): Normal cells have a fixed life-span.
- Ability to metastasise and invade
- Ability to produce own blood supply (angiogenesis)

The common causes of cancer can be divided into:
- Radiation eg UV light, ionising radiation, nuclear radiation exposure
- Infection eg H.Pylori (stomach cancer), schistosomiasis (bladder cancer), Hepatitis B & C (liver cancer)
- Genetic abnormalites eg Familial Adenomatous Polyposis, Li Fraumeni Syndrome
- Chemicals eg aniline dye (bladder cancer), cigarette smoking
- Others eg diet, chronic irritation (Marjolin's ulcer)

Treatment options for Cancers include:
- Radiotherapy
- Chemotherapy
- Surgery
- Hormonal Therapy
- Molecular Targeted Therapy

Stomach Cancer

Stomach cancer is one of the common cancers. It is more prevalent in Japan & South America. The incidence increases with age and there is a slight male preponderence.

Stomach Cancer as seen thru an OGDS

The risk factors for stomach cancer include:
-H.Pylori infection
-smoked food
-preservatives/high salt diet
-smoking/alcohol consumption
-pernicious anaemia
-previous gastrectomy (stomach surgery)
-stomach polyps
-genetics: blood group A, hypogammaglobulinaemia

Patients who have stomach cancer may present with:
-upper abdominal pain
-loss of weight
-loss of appetite
-early satiety
-persistent vomiting
-vomiting blood (haematemesis)
-passing blackish stools (malaena)
-symptoms of gastritis such as dyspepsia, belching

Or they may be asymptomatic.

To confirm the diagnosis, an Oesophago-Gastro-Duodeno-Scopy (OGDS/EGDS) should be done. The OGDS will be able to visualise the tumour and assess the size and also stop any bleeding. A biopsy from the tumour can be obtained with the OGDS to confirm the diagnosis.

To properly assess the extent of spread of the cancer, the patient should undergo a CT-scan or MRI or PET scan. Endoscopic ultrasound is able to assess the depth of the tumour. And staging Laparoscopy will be able to properly stage the cancer and assess for peritoneal deposits.

Fungating Stomach cancer noted in a resected specimen

The cure for stomach cancer is surgery. A subtotal or total gastrectomy (surgical excision of the stomach) can be done. The type of surgery will depend on the stage of the cancer and also the patient's fitness for surgery. Curative surgery (D2 classification) includes surgical excision of the stomach with a clear micro & macroscopic margin, removal of lymph nodes one level beyond those involved &  removal of the omentum, spleen and distal pancreas.

Currently, based on the MAGIC Trial, a 3 cycle neoadjuvant (pre-operative) chemotherapy is recommended followed by surgery and another 3 cycles post-surgery. This has been shown to downstage the cancer, improve resectability and improve overall survival for the patient.