What is Cancer Screening?
Cancer screening is for healthy individuals with education. It refers to detection of cancer at very early stage so that earliest possible treatment can be instituted. Rather than going for unnecessary blind tests, program for screening should be planned in consultation with your oncologist as requirements are different for different cancers and differs as per age groups and gender.
What are the benefits of cancer screening?
Early detection of cancer means achieving complete cure. Recurrence rate increases and prognosis becomes poorer as the stage of cancer increases. Early detection leads to early appropriate treatment and sufferings of cancer can be prevented.
What are the modalities for cancer screening?
Tests for screening are such that they are readily available, can be applied for mass population and has shown definite benefits.
- Clinical examination eg for breast cancer, prostate cancer
- Blood tests eg PSA for prostate cancer
- Radiological imaging eg Mammography for carcinoma breast
- Cytology eg PAP smear for cervical cancer
- Endoscopy eg colonoscopy for colon cancer
Positive cancer screening tests needs to be confirmed further for cancer by appropriate tests.
Which Cancers can be detected by screening?
Screening is not shown to be beneficial in all cancers. Following cancers have shown benefit by screening:
- Breast cancer (up to 30% decrease in mortality)
- Cervix Cancer (up to 70 % decrease in mortality)
- Colon Cancer (up to 25% decrease in mortality)
- Lung Cancer (up to 20% decrease in mortality in chronic smokers)
- Prostate Cancer
- Awareness regarding problems is more important and any symptoms or problem should be treated only under supervision of a doctor.
What are the recommendations for Cancer Screening?
Screening for Breast Cancer:
- Mammography : US Preventive Services Task Force (USPSTF) recommends mammography once in every 2 year for females between age group 50-75 years. Women with a family history has a benefit of starting at age 40 years. after 75 years there are insufficient evidence of benefit of screening mammography
- Breast Self Examination and annual Clinical examination: breast self examination is easy to learn and and any abnormality should be reported to the oncologist.
- For High Risk/ Genetic risk factors: screening should start by age 25 or 10 years earlier of youngest relative affected. Annual mammogram and MRI or Doppler ultrasound alternating at 6 month interval can be considered.
Screening for Cervix Cancer
- Cervical cancer screening is most effective screening programme of any cancer disease resulting in significant decrease in mortality from carcinoma cervix
- United state preventive services task force (USPSTF) recommend cervical cancer screening starting at age 21 yrs
- Between age 21-30 years cytology recommended at 3 year interval and HPV testing is not recommended
- Between 30-65 years cytology every 3 year or cytology +HPV testing every 5 year
- If previously adequately screened screening can be discontinued after 65 years
- Women with prior total hysterectomy and no CIN can discontinue screening
Screening for Colon and Rectal Cancers:
- United State Preventive Services Task Forces (USPSTF) recommends screening for colorectal cancer using fecal occult blood testing, sigmoidoscopy, or colonoscopy in age group 50 years – 75 years
- USPSTF doesn’t recommend screening in age group 76-85 years although supported by some
- There is no evidence to support screening after 85 years. There are insufficient evidence evidence to support computed tomographic colonography and fecal DNA testing as screening modalities
- Colonoscopy is done at interval of 10 years. In individuals with genetic risk factors it is started early, 10 years earlier than the youngest family member affected or in 20s
Screening for Lung Cancer:
- Age group 55-80 yrs with a history of smoking
- United States Preventive Services Task Force (USPSTF) recommend annual screening for lung cancer with low dose computed tomography in adults aged 55-80 years who have a 30 pack year smoking history and currently smoke or have quit within past 15 years. Screening should be discontinued once a person has not smoked for 15 years or develops a health problem that substantially limits life expectancy or the ability or willingness to have curative lung surgery.
Screening for Prostate Cancer:
- The United States Preventive Services Task Force (USPSTF) recommends against routine screening for prostate cancer. It recommends that regardless of age, men without symptoms should not routinely have the prostate-specific antigen (PSA) blood test to screen for prostate cancer.
- American Cancer Society recommends that individual should have active discussion with oncologist about screening and should take place at age of 50 years for men who are at average risk of prostate cancer and are expected to live at least 10 more years.