All of us know that prevention is better than cure and its importance cannot be overemphasized. However, not every disease is preventable and screening provides us with the second best option by catching them early. Although there are various definitions for screening it can simply be summed up as detecting disease early in asymptomatic (those without any symptoms) individuals.
SCREENING – WHY AND WHEN ?
It is estimated that screening results in mortality reduction ranging from 3 to 35% depending on various factors. Cervical cancer is an excellent example of mortality reduction as a result of screening. Apart from reduction in deaths from cancer, screening also gives us an opportunity to detect cancer at a stage where minimal treatment is required. For example, a very early breast cancer may just require a small surgery and the patient may be able to avoid chemotherapy and radiation therapy completely. Also, most of the screen detected cancers would require less mutilating operations with much lesser hospital stay and the cost of treatment. However, you must discuss the pros and cons of any screening investigations with your oncologist before having it done.
SCREENING – HOW ?
Screening can be broadly divided into having following components:
1. Self examination (wherever feasible)
2. Examination by a trained health personnel (clinician or a paramedical staff specifically trained for screening)
3. Appropriate investigations
GENERAL GUIDELINES (for normal risk general population)
High risk individuals by virtue of their family history, habits or any other risk factor need to be counselled separately and usually require more intense screening methods.
Breast Cancer screening
- Self examination periodically starting at the age of 20 years
- Clinical examination 1-3 yearly between 20-40 years and yearly after 40
- Mammogram every 1-2 years after 40-50 years of age.
Cervical Cancer Screening
Should begin approximately 3 years after beginning of vaginal intercourse
It includes pelvic examination every 3 years and Pap smear yearly for three years and, if found normal for three consecutive years, thereafter the frequency can be decreased. If pap smear is combined with HPV DNA testing the frequency of screening can be decreased and it can safely be done every three years
Colon Cancer screening
One of the following is recommended for a normal risk individual above 50 years of age:
1. Colonoscopy (endoscopy of large intestine) every 10 years
2. Stool test of occult blood yearly and 5 yearly sigmoidoscopy (only partial endoscopy of large intestine)
3. Double contrast barium enema every 5 years
Individuals with family history of colon cancer or personal history of precancerous lesions like polyps (small benign growths in colon / rectum) require the screening to begin at a younger age and done more frequently depending on the level of risk.
A combination of clinical examination and serum PSA test (blood test) may be beneficial in reducing deaths for individuals between the age of 55 and 69 years.
Although there are no guidelines for oral cancer screening (largely due to the fact that it is a unique problem of our country and is seen much less in developed), it is a good idea to keep doing monthly self-examination of inside of the mouth for any ulcer, white or red patches and neck for any lump.
Screening is an effective tool to diagnose cancers at a pre-clinical stage thereby providing an opportunity to attain high cure rates by using less aggressive treatment options thus improving the quality of life as well.
1. Screening is a strong tool to detect cancer at an early stage
2. Screening has been found to reduce death due to cancer significantly in some cancers
3. It is not cost effective for all cancers and must be done under specialist guidance
4. Individuals at higher than normal risk of a particular cancer by virtue of family or personal history require more intense screening
5. Be alert towards warning symptoms / signs (see box) and get expert opinion on it.