What is Cancer screening?

# Cancer screening

- What is Cancer screening?
- Why to do screening?
- Who should do cancer screening?
- Cancer screening in general population.
- Cancer screening in high population.

What is screening?
Screening for cancer involves examination and investigations done on a person to detect occurrence of cancer in an early stage itself.

Why do screening?
It is a form of secondary prevention, in the sense that screening does not prevent the occurrence of cancer, but detects it early, allowing effective treatment and reduction in mortality.

Most of the risk factors for cancer are preventable. Eliminating the use of tobacco products and secondhand smoke exposure, getting vaccinated (HPV-Human Papilloma Virus), avoiding tanning beds, maintaining a healthy weight, staying physically active, avoiding processed or red meat, consuming a healthy diet with a high intake of fruits and vegetable are some of the measures that can substantially decrease a person's lifetime risk of developing or dying from cancer.

Who should do screening?
In general population, screening is done for breast cancer, cervical cancer and colonic cancer.

High risk population screening for lung cancer can be done for those age above 55 years with history of heavy smoking. Similarly high risk screening can also be done for familiar cancers running in the families like BRCA gene in breast and ovarian Cancer. Less commonly pancreatic, prostatic, male breast cancer.

Screening in general population

Screening for breast cancer: All who are more than 50 years should undergo mammogram once in two years as recommended by most societies. Some societies recommend those between age of 40 to 50 years should get an opportunity for screening. The screening should continue up to the age of 74 years. After that screening should be decided individually, depending on the life expectancy, and based on the decision between the physician and patient.

Screening for Cancer cervix - The age at which screening for ca cervix should start differs between recommendations by different groups or societies. ASCO suggests 21 years, whereas UK guidelines recommends to start at 25 years. The concept is at the screening for cervix as to start for all women who has been exposed to HPV infection after a sexual contact. The screening includes performing a gynaecological examination and taking a Pap smear, HPV testing or both. If a smear alone is done, the testing has to be the period once in three years, whereas if HPV test is being done or if both are done together, then the frequency of testing can be reduced to once in five years. If there is any suspicious finding in any of these Pap smears, there are specific recommendations as to how to proceed further with repeat tests, or for colposcopy and biopsy to be done. Screening has to end at 65 years, for those who had more than three recent tests reported as negative.

Screening for colonic tumours has to be done for all people above the age of 45 or 50 years with different methods for screening, ranging from a simple stool test to check if there is blood content in stools, video/capsule colonoscopy (swallowing a small capsule, which will capture the video of the entire GI tract while passes through your stomach and bowels), conventional colonoscopy, which includes passing a tube up your rectum to check the inner part of the large bowel by the gastroenterologist. This will be test has to be done done once in a year. Colonoscopy, which is considered the gold standard for screening, has to be done once every 10 years. If sigmoidoscopy is done, it has to be done once in five years. Any patient who has a suspicious Guaiac based stool tests, should undergo colonoscopy.

High risk population screening:

High risk cancer screening includes screening for cancers in those who are at a higher risk for that cancer to occur, due to their habits or due to familial inheritance of a gene(s) for that cancer.

Lung cancer: Those who are in the age group of 55 to 74 years (some recommend 80 years) and who have smoked more than 30 pack years, should undergo lung cancer screening. What is a pack year? A person who smokes one pack of cigarettes (1 pack= 20 cigarettes) for one year, is said to have smoked one pack year. Such persons should undergo a low dose CT scan of the chest to look for any early tumour. This will expose to radiation only a little more than that of the chest X ray, while standard CT scans have higher radiation exposure.

Breast cancer high risk screening:
Those who have an increased risk for breast cancer includes 1) a person known to have BRCA mutation on testing 2) BRAC not tested, but a first degree relative has BRCA, 3) high score in risk estimation models 4) received chest radiation for lymphoma before age of 30 years 5) has any other cancer syndromes like Cowden syndrome, Li Fraumeni etc. Any of these above groups are to undergo mammogram annually (instead of the once in 2 years recommendation for normal population). Also it is advised for these high risk people to undergo a MR (magnetic resonance) mammogram i.e. MRI of the breast than a conventional mammogram.

Screening for prostate cancer
Men who are between the ages of 5 to 69 years can undergo prostate cancer screening after discussion with them about the potential benefits and risk of screening. Those who have one first degree relative (father or brother) with prostate cancer less than 65 years, and African American race should receive information about screening at 45 years and beyond.Those with multiple first degree relatives, should start screening at 40 years.
Screening is done with blood test- PSA (prostate specific antigen) and/or with DRE digital rectal examination. For those men with hypogonadism, DRE should always be done, as PSA alone is less sensitive. PSA less than 2.5 can continue testing once in 2 years, whereas those with more than 2.5 needs yearly testing, If PSA more than 4.0, should undergo further evaluation and biopsy.

High risk for colon cancer
CRC (colorectal cancer) high risk are those who have one first degree relative with colorectal cancer or an advanced adenoma at age less than 60 years; or those with two first degree relatives with the above at any age. Screening recommended for such persons is colonoscopy every 5 years (rather than 10 years for average risk population).

Screening for all cancers cannot be done as they are not common enough or are not possible to be detected by tests at an earlier stage to reduce treatment mortality.

## Issues in India:
In our country, we have opportunistic cancer screening. This means performing screening tests on a person who has reported to the health care provider or hospital for another complaint. Developed countries have established cancer screening guidelines in place. Since cancer has become the new epidemic there is a urgent need for unified cancer screening programme in our country.

_Here at Holy Cross hospital, we offer you screening for cancer for the average risk population, and also consultation and advice for genetic screening for high risk population._