Wed, 02 Aug 2000

Learning the ins and outs of cancer

Starting this week, The Jakarta Post and Singapore-based Parkway Group Healthcare will jointly run an interactive health column on various medical topics. The column will appear twice a month. Readers are encouraged to ask questions through The Jakarta Post's, or Parkway's san-

SINGAPORE: The very word 'cancer' generates fear not only among the victims but also the public at large. To allay fears and correct misconceptions about cancer, public education is a must.

The exact mechanism that causes cancer is still unclear, but several factors have been identified as carcinogenic or cancer producing.

Some cancers can be prevented but not all. Most lung cancers, for instance, can be prevented by not smoking. Although many cancers cannot be prevented, early screening and detection improves greatly improves the chances for successful treatment.

Dr. Hoe Ah Long, a consultant surgeon at Gleneagles Medical Center in Singapore, prepared the following article for The Jakarta Post's readers on the importance of cancer screening.

What is the aim of cancer screening?

The aim of cancer screening is to detect cancer early so that with effective treatment, the patient can live longer.

How does it work?

When a cancer grows, it goes through an initial stage when it is small and asymtomatic. If we can detect the cancer at this stage, it probably has not spread elsewhere and is easier to treat.

What are the advantages of screening?

When a cancer is detected and treated at the early stage, there are several advantages.

* Better survival

* Less mutilating surgery

* Less toxic chemotherapy or avoidance altogether.

* Less expensive treatment

* If no cancer is detected by screening, a person can feel more reassured.

Which cancer is suitable for screening?

There is a criteria to judge which cancer (or disease) is suitable for screening.

* It is a common cancer

* The cancer must have an early phase that can be detected by diagnostic methods.

* The diagnostic test should be simple, accurate and not harmful for the patient.

* Effective treatment is available for the cancer detected at the early stage. The treatment should be less extensive or toxic to the patient.

* The process of cancer screening and treatment should be cost effective.

Who should be screened?

Cancer is more common in older age groups and cancer screening is usually recommended for people above 40 years of age. An exception is screening for cervical cancer which is recommended for women from 20 years old.

People who belong to a high risk group should consider starting screening at an earlier age (thirties). High-risk group refers to people who have one or more risk factors for a cancer.

Breast: Family history of breast cancer, no children, obesity, heavy meat and fat diet.

Colorectal: Previous history of colonic polyps, ulcerative colitis, family history of colon cancer.

Cervical: Sexual activity at early age, multiple partners, herpes, infection, smokers, poor personal hygiene.

Liver: Liver cirrhosis, chronic hepatitis B infection.

What are the methods of screening?

Screening tests vary from determination of tumor markers in the blood, to body fluid analysis (sputum, stools), x-rays and interventional methods such as endoscopy.

The criteria for a good test is:

* Good sensitivity to detect more cancers (low false negative rate)

* Good specificity to accurately diagnose people without the cancer (low false positive rate)

* Simple, acceptable to the patient

* Inexpensive

* Cause no harm. This is important as screening is performed on healthy individuals.

When should it be done? In order for screening to be effective, it should be started at the appropriate age and repeated at regular intervals. A single negative screen does not mean that an individual is free of cancer for life.

Is there any proof that cancer screening works? Yes, large scale studies have shown that screening for breast and cervical cancers have reduced the death rates for these cancers. However, similar studies have not proven the effectiveness of screening for lung, colon, or prostate cancers.

How is it done?

* Cancer watch

* Physical examination

* Screening Tests

Cancer watch -- look out for warning signs of cancer?

* A persistent ulcer or lump on the skin, in the mouth or nose

* A breast lump or nipple discharge

* Change of bowel habits or rectal bleeding

* Abnormal vaginal bleeding

* Any persistent symptom (more than 1 month duration)

What are the disadvantages of cancer screening?

* The diagnostic tests may be painful and unacceptable to the individual. It can also be potentially harmful.

* For an individual with a false positive result, he/she has to undergo further tests and possibly a surgical biopsy to rule out cancer.

* Conversely, for an individual with a false negative result, he/she may be falsely assured.

What are the current recommendations for cancer screening?

* Breast Cancer. Women above 40 years old (younger for high risk group, see above) are suggested to perform monthly self examination, have clinical breast examination yearly and annual mammogram.

* Cervix. Women of 25 years and above are suggested to have PAP smear every 3 years (after three negative smears, less frequently at discretion of the doctor).

* Colon, Rectum. Men and women over 50 are advised to have faecal occult blood test yearly, sigmoisdoscopy three to five yearly. From 40 years, digital rectal examination is suggested.

*Lung. People of all ages are advised to have an annual chest x- ray and sputum cytology.

*Stomach. Digital rectal examination and PSa tumor marker annually for men 50 to 70 years old.

*Liver. Alpha feto-protein tumor marker and ultrasound liver every six months only for high risk groups.