Cancer Screening - What, When and How?

Introduction

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 of 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?

Screening is meant to decrease mortality from the disease in question and it can be utilized effectively for fairly common health problems where cost effective screening methods and clinically effective early institution of treatment is possible.

It is estimated that screening results in mortality reduction ranging from 3 to 35 percent 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:

• Self examination (wherever feasible)
• Examination by a trained health personnel (clinician or a paramedical staff specifically trained for screening)
• Appropriate investigations

Which Cancers To Screen For?

Screening proven to be beneficial

• Breast cancer
• Cervical cancer
• Colorectal cancer (large intestine and rectum)

Screening not proven to be beneficial

• Lung cancer
• Ovarian cancer
• Testicular cancer

Screening beneficial is high-risk region or population

• Liver cancer
• Oral cancer
• Esophageal (food pipe) and Stomach cancers

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 counseled separately and usually require more often and 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:

• Colonoscopy (endoscopy of large intestine) every 10 years
• Stool test of occult blood yearly and 5 yearly sigmoidoscopy (only partial endoscopy of large intestine)
• 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.

Prostate Cancer

Studies have been contradictory. Nonetheless, 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.

Conclusion

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. Notwithstanding the utility of screening, one must weigh the benefits and risks carefully before undergoing screening.

Key Points

• Screening is a strong tool to detect cancer at an early stage
• Screening has been found to reduce death due to cancer significantly in some cancers
• It is not cost effective for all cancers and must be done under specialist guidance
• Individuals at higher than normal risk of a particular cancer by virtue of family or personal history require more intense screening
• Be alert towards warning symptoms / signs (see box) and get expert opinion on it.

Warning symptoms / signs of cancer

• A new lump / bump anywhere in the body specially if it is painless and is growing
• Abnormal bleeding
  • Excessive bleeding during periods or bleeding between periods or after intercourse
  • Blood in stool, urine, sputum or vomit
• Difficulty in swallowing or painful swallowing in absence of throat infection
• Change in bowel habits - type of stool, frequency of stool
• Change in urinary habit - increased frequency, thin stream, straining while passing, blood in urine, difficulty in beginning, feeling of incomplete evacuation
• Unexplained cough lasting for more than 3 weeks inspite of treatment
• Hoarseness in voice lasting for more than 3 weeks inspite of treatment
• Ulcer that is not healing (e.g. mouth ulcer)
• A mole that is changing color (usually gets darker), starts to itch or bleeds.
• Long standing dyspepsia (excessive gas / acidity symptoms)
• Unexplained weight or appetite loss.

Please remember, all these warning signs and symptoms can also be because of benign (non-cancerous) diseases. Nonetheless, they need to be investigated to find and treat the cause.