SINGAPORE — In Singapore, an average of 46 people were diagnosed with cancer daily and 16 people died of cancer each day for the period from 2017 to 2021.
One in four people may develop cancer in their lifetime, the Singapore Cancer Society also states on its website.
So screening for cancer is not such an abnormal thing to do.
Do you know, for example, that there is a national screening program, or that there are screening guidelines for some common cancers such as colorectal, breast, and cervical cancers?
And if you want to get started, do you know which tests to take for cancer detection?
For instance, do you need to check the boxes for all the tumor-marker tests that add to your total bill when you go for a health screening package?
Early detection and treatment are key to better clinical or management outcomes with cancer. TODAY speaks to some doctors to determine what to consider when screening tests.
As is usual, people generally do not think that they will get cancer, especially if they perceive themselves as being rather healthy.
Take 41-year-old Amaliah Othaman, who is Singaporean and has two children.
She decided in 2019 to get her health checked after finding a lump in her breast and it turned out to be benign.
“From there, I thought that maybe I should just check out what screenings are available and go for them,” she said.
She came upon a free Pap smear or a Pap test offered by the Singapore Cancer Society.
In her mid-30s at the time, she had never gone for a Pap test that involves collecting cells from the cervix, which is located at the lower part of the womb.
Women who are 25 years old and above and have never had sex are recommended to go for cervical cancer screening.
The test saved her life. The results came back to show that she had Stage 1 cervical cancer.
Recalling her shock upon learning of the diagnosis, she said: “I remembered wondering, ‘How is it possible?’ I felt perfectly fine – I had no symptoms, was living an active life, and seldom fell sick.”
The cancer diagnosis was a big wake-up call to take her health screenings seriously, she added.
Having gone for treatments and survived cancer for almost five years, Ms Amaliah now encourages her family and friends to get screened regularly for peace of mind.
“The doctor told me that I was very lucky to detect the cancer early,” she said.
Yet, even at that early stage, the treatment involved a major hysterectomy surgery that removed the entire womb, she added.
Cancer screening may help detect early signs of cancer, sometimes even before symptoms appear.
The Screen for Life program is a national screening program that offers eligible Singapore citizens and permanent residents subsidized screenings.
1. For colorectal cancer screening, the fecal immunochemical test — where a small stool sample is collected for a test — is recommended for people aged 50 and above, to be done every year
2. For breast cancer, a mammogram is recommended once every two years for women aged 50 and above. Women in the 40 to 49 age group are also eligible for a mammogram once a year if their doctor has recommended them to go for it
3. For cervical cancer, a Pap smear every three years is recommended for women in the 25 to 29 age group who have ever been sexually active. For those aged 30 and above, a human papillomavirus (HPV) test is recommended every five years.
The screening methods above for the colon, breasts, and cervix have been shown to effectively detect cancer at an earlier stage.
In some cases, screening may be able to detect even a pre-cancer development, which is the presence of abnormal cells that could pose a greater risk of becoming cancerous.
Colorectal cancer is an example of a well-studied cancer that can be detected even before the actual disease develops.
The fecal immunochemical test is a preliminary cancer screening test that detects the presence of small amounts of blood in stools. However, the presence of blood does not mean that the person has cancer; further tests are needed.
Dr. Melvin Look, a specialist in gastrointestinal cancer surgery and director of PanAsia Surgery clinic, said that a positive fecal immunochemical test should be followed by a colonoscopy for screening.
The procedure for a colonoscopy involves preparation the day before of drinking a laxative solution to clear out all solid contents in the intestines.
Then, for the scope, a long flexible tube with a light and a tiny camera is placed through the anus into the end of the large intestine to look for abnormalities along the intestinal walls and tract.
Dr Samuel Ow, Singapore Cancer Society’s council member and chairperson of the society’s community health committee, explained how colonoscopy can potentially detect cancer at a very early stage, even in a pre-cancer stage.
“We know that there’s a continuum. “It begins from normal colon tissue to a benign polyp (benign lumps that form on the inner wall of the colon and rectum), to a polyp that is starting to develop changes, to a pre-cancer polyp, then to invasive cancer.
“This whole developmental process can take a decade or longer.
“Therefore when I speak to my patients about screening for colon cancer, I will pitch to them that I’m actually not trying to detect cancer; I’m trying to detect the precursor of cancer and nip it in the bud.”
Dr Ow is a senior consultant with the Department of Haematology-oncology at the National University Cancer Institute, Singapore.
Dr Look said that the availability and uptake of screening tests in Singapore have helped detect some cancers earlier.
For example, about 42 percent of men with colorectal cancer are diagnosed in the early stages, compared to 19 percent for lung cancer. For women, more than three-quarters of them (77 percent) with breast cancer are diagnosed early, whereas only 37 percent of stomach cancer is diagnosed in the early stage, he said.
One question you might ask is why are other forms of “common” cancer such as stomach cancer and lung cancer not on the national screening program.
And with so many types of cancers to watch for, why are there not more routine screening methods to check every organ?
Dr Tanujaa Rajasekaran, senior consultant medical oncologist at Parkway Cancer Centre, said that not all cancers have well-established screening methods.
Breast, colon, and cervical cancers are included in the national screening programs because they meet several criteria• They are relatively common
• There are effective screening methods available
• Early detection has been shown to significantly improve outcomes for these cancers
“On the other hand, even though lung, prostate, and stomach cancers are also common, there may be challenges with implementing effective screening programs for these cancers,” Dr Tanujaa said.
“For example, there may not be highly accurate and cost-effective screening tests available for these cancers that can reliably detect them at early stages.
“Additionally, the risk factors for these cancers may not be as well-understood or easily identifiable as those for breast cancer, colon and cervical cancers.”
Certain screening procedures may also be invasive and pose potential risks that do not justify the benefits of screening an entire population.
For example, the current methods to assess the pancreas is through “very invasive” scopes or computed tomography (CT) scans, which come with radiation, Dr Ow said.
In Singapore, pancreatic cancer is the 10th most common cancer among men and the ninth most common one among women.
However, its aggressive nature makes it the fourth most common cause of cancer deaths here.
Dr Ow said: “You can argue that a colonoscopy (that screens for colon cancer) is very invasive, but the frequency that we do a colonoscopy is typically about every 10 years. And so, that’s sort of worth it because we know the continuum is long.
“But for an organ like the pancreas, we don’t know what the continuum is. Do we offer this yearly? Can we offer this half-yearly?
“Also, how do we get tissues from the pancreas? We will have to do a biopsy through a scope. You can imagine that there’s this invasiveness, potential harm, side effects, and so forth.”
Dr Ow also said that apart from the potential medical risks, unnecessary invasive screening procedures can affect people psychologically and can be cost- and time-consuming.
There is also now evidence to suggest that screening may sometimes detect cancers that are very slow-growing, or indolent, that may not actually require any treatment, Dr Tanujaa said.
For some slow-growing cancers, the treatment strategy may be just watchful waiting, which means closely monitoring the patient without giving any treatment until changes occur, Dr Ow said.
“Studies have shown that if you do autopsies of elderly men, many of them may have had prostate cancer but they (did not) die of it.
“So that’s why there’s something called a lead-time bias’ because we don’t know whether or not some cancers picked up by tests can affect lifespan or affect the quality of life. Prostate cancer that is slow-growing is (an example),” he explained.
Lead-time bias occurs when screening finds a cancer earlier, but the earlier diagnosis does not change the course of the disease.
The current national screening recommendations for cervical, breast, and colon cancer apply to people with average risks and no symptoms.
For those with more risk factors, extra or early screening may be appropriate.
“Individuals with a strong family history of certain cancers may benefit from starting cancer screening at an earlier age or undergoing more frequent screening than the general population,” Dr Tanujaa said, adding that the decision should be made in consultation with a healthcare provider.
For instance, women with a family history of breast cancer, especially if it involves first-degree relatives such as a mother or sister, may be advised to start mammography screening at an earlier age than the general population.
Dr Tanujaa said that it is generally recommended to start breast cancer screening 10 years younger than the first-degree relative when she was diagnosed with breast cancer.
Genetic counseling and testing for mutations in the BRCA1 and BRCA2 genes may be recommended for those with a strong family history of breast or ovarian cancer, she advised.
People with a family history of colorectal cancer or certain hereditary syndromes, such as Lynch syndrome or familial adenomatous polyposis, may also need to begin colorectal cancer screening earlier than the recommended age of 50.
This may involve starting colonoscopy screening in their 40s or even earlier, depending on their family history and genetic testing results, Dr Tanujaa said.
Another example is liver cancer screening for people with a history of liver cirrhosis or chronic hepatitis B infection.
Some screening packages include a panel of tumor-marker tests that claim to be able to detect certain cancers early.
However, relying on such tests to screen for cancer can potentially do more harm than good.
Dr Tanujaa said that tumour-marker tests measure certain substances in the blood, urine, or tissue that can be elevated in the presence of cancer.
“While they can be useful in some specific situations such as monitoring the response to cancer treatment or detecting cancer recurrence in individuals already diagnosed with cancer, they are generally not recommended for routine cancer screening in asymptomatic individuals,” she added.
Dr Look from PanAsia Surgery said that due to its low sensitivity, cancer markers are not useful as a cancer screening test.
“Cancer markers can be totally normal even in a patient with very advanced cancer, and it may give a false sense of security in assuring the patient that he or she doesn’t have cancer.
“Cancer markers can also be elevated due to non-cancer causes, causing a false sense of alarm when they are used for general screening,” he added.
It helps to understand your personal health history before you put a chunk of money down for screening tests.
“Knowing your family history of cancer, previous cancer diagnoses, and other relevant medical conditions can help individuals assess their own risk factors for specific types of cancer,” Dr Tanujaa said.
She also advised people to educate themselves on the recommended screening guidelines, based on age, gender, and other risk factors.
They may consult their healthcare providers to get more personalized recommendations.
Dr Ow from the Singapore Cancer Society said that it is also important to follow the recommended screening schedule, or as advised by a doctor.
“(Cancer screening schedules) are not static,” he said.
“For example, for HPV and Pap smears, the schedule may be between every three and five years, but there’s also an adapted strategy.
“If there are some slight changes that need to be followed up on, it may not be three to five years later; it may be six to 12 months.”
And just because you go for a screening once under the recommended guidelines and the results are normal, it does not mean that you can stop doing the checks forever and not keep up the schedule for the next check. It is not a one-time thing.
Dr Ow said: “We have patients with an abnormal mammogram (findings) who did a biopsy, found out that it’s benign, everything’s normal, and that’s the last mammogram they went for (and they do not do it again) because they felt that everything was okay.”