MARCH: COLORECTAL CANCER AWARENESS MONTH
WHAT DO WE KNOW?
Is colorectal cancer(CRC) an important public issue?
Colorectal cancers are the second leading cause of cancer deaths in western countries and India is quickly catching up with the incidence of developed countries due to the changing lifestyle and food habits. The incidence rates of CRC in Indian immigrants to the United Kingdom and USA are much higher, suggesting that life styles and dietary habits are important in the causation of the CRC. This also means that with economic transition from a low income to middle income economy, there will be a big increase in the burden of CRC in India. (Ref: Indian J Gastroenterol (Jan–Feb 2011) 30(1):3–6)
What are the risk factors for CRC?
Family History, Obesity, Lack of Physical Activity, High fat diet, Low fiber intake, inflammatory bowel disease, Red meat intake, Alcohol intake, Tobacco usage.
What are the symptoms of CRC?
Bleeding per rectum, Altered bowel habits, Abdominal Pain, Sense of incomplete defecation, Tenesmus, Loss of weight, Anemia, intestinal obstruction in some cases.
How to evaluate patients with suspected CRC?
Most of the patients with bleeding per rectum are treated for a long time as haemorrhoids. This results in delay in diagnosis and progression of the disease.
All patients presenting with bleeding per rectum must undergo a digital rectal examination and a proctoscopic examination. Without a proctoscopy, they should not be branded as haemorrhoids. For patients above 50 years of age, even if the rectal examination reveals haemorrhoids, colonoscopy should be done to rule out colo- rectal cancer as the haemorroids could be secondary to the rectal cancer.
Fecal Occult Blood may be helpful. However a negative FOBT does not rule out CRC.
What further investigations are done after diagnosing CRC?
Proctoscopy and colonoscopy play a major role in the diagnosis of CRC. Once a colonoscopic biopsy confirms malignancy, further staging work up is done to assess the extent of the disease. When a proctoscopy and biopsy confirms rectal cancer, colonoscopy should still be done to rule out synchronous lesions in the rest of the large bowel unless there is an obstruction.
For accurate staging of the disease, we recommend MRI Pelvis (for rectal cancers only), CT Abdomen & Chest. This will give most of the information required in deciding on further management.
Apart from the routine preoperative blood investigations, Serum CEA ( Carcino Embryonic Antigen) should be measured before treatment.
Other investigations like Endoscopic Ultrasound and FDG PET CT are done in special situations only and not as routine.
How to stage CRC?
Management of CRC depends on the stage of the disease.
STAGING OF CRC (As per NCCN 2015)
|Tx : Primary Tumour cannot be assessed||N1a: Metastases in 1 regional lymph node||M1a: Metastases confined to one organ/site|
|T0 : No evidence of primary tumour||N1b: Metastases in 2-3 regional lymph nodes||M1b: Metastases in more than one organ/site or peritoneum|
|Tis : Carcinoma In Situ-Intraepithelial / invasion of lamina propria||N1c: Tumour deposits in the subserosa/mesentery without nodal involvement|
|T1 : Tumour invades submucosa||N2a: Metastases in 4-6 nodes|
|T2 : Tumour invades muscularis propria||N2b: Metastases in > 7 nodes|
|T3 : Invades through muscularis propria into pericolorectal tissues||Minimum of 12 – 15 nodes should be removed||Stage 0: TisN0M0
Stage I: T1/T2,N0M0
Stage II: T3/T4,N0M0
Stage III: Any T, N1,M0
Stage IVA: AnyT, Any N, M1a
Stage IVB: Any T, Any N, M1b
|T4a : Penetrates to the surface of the visceral peritoneum|
|T4b: Directly invades or adherent to adjacent organs or structures|
How to treat colon cancer?
Polyps are removed by endoscopy itself. If a poypectomy specimen showed invasive cancer, for pedunculated polyps no further treatment is required. For sessile polyps or fragmented specimen where margin status not assessed, colectomy with en bloc removal of regional lymph nodes is required.
If there is a growth and biopsy proved malignancy, operable cancers based on CT scan without obstruction should undergo colectomy with en bloc removal of lymph nodes. For operable cancers presenting with obstruction or per operative finding of colonic growth, standard colectomy with lymphadenectomy in one stage or as staged procedure should be done.
For resectable metastases present in one organ like liver or lung only, synchronous resection of the primary and metastases followed by chemotherapy is the preferred treatment. However, 2 -3 cycles of chemotherapy followed by surgery or resection of primary first followed by 2 -3 cycles of chemotherapy followed by resection of the metastases and completion of chemotherapy are other options.
For inoperable growths/inoperable metastatic disease at presentation, chemotherapy followed by reassessment for surgery is the standard. For inoperable disease even after chemotherapy or if peritoneal metastases are present, palliative chemotherapy is given.
Newer monoclonal antibodies like cetuximab, panitumumab, bevacizumab are used along with chemotherapy wherever appropriate.
Who should receive chemotherapy after surgery?
Selected stage II and all stage III and IV cancers must receive chemotherapy. Medical oncologist opinion should be obtained for all cases other than stage I.
How to treat Rectal cancer?
Treatment of rectal cancer depends on the stage and the location of the tumour in relation to the anal sphincter. Polyps are managed similar to colonic polyps.
T1,T2 tumours with N0 can be managed with surgery which requires a total mesorectal excision. Sphincter preserving surgery to be done unless the sphincter is involved or a minimum of 2 cm distal margin is not possible. Uses of preoperative chemoradiation and stapler devices have nowadays drastically reduced APR surgeries.
For T3, T4, Node positive diseases, preoperative chemotherapy and radiation therapy should be given. Surgery should be done 6 – 8 weeks after completion of RT and chemotherapy should be continued after surgery. All T3/T4/Node positive cases detected during preoperative evaluation must be referred to a medical and radiation oncologist before embarking on surgery.
How to prevent CRC?
Regular physical activity, avoiding obesity, avoiding alcohol and tobacco, avoiding fatty foods and red meat, intake of fruits and fresh vegetables daily, increasing fiber intake and regular screening will definitely prevent CRC.
What are the screening guidelines?
As per the American Cancer Society guidelines, all people above the age of 50 must undergo annual digital rectal examination, annual fecal occult blood test, and colonoscopy once in 10 years. Those with family history of CRC must get a genetic counselling and start screening earlier.
What can we do in general practice to control the burden of CRC in our country?
Educate our patients and relatives to undergo colonoscopy screening after the age of 50. Always do a digital rectal examination and proctoscopy before treating haemorroids. Avail multidisciplinary team opinion before treating locally advanced colorectal cancers. Pass on the information to all.