SINGAPORE - Some doctors are calling for more people to be screened for lung cancer in the hope that this will lead to earlier diagnosis and better outcomes. Cancer accounts for more than 28 per cent of deaths in Singapore, with lung cancer the biggest killer.
The latest data from the Singapore Cancer Registry for the five years from 2017 to 2021 showed that lung cancer killed about 100 people here each month – which is 36 per cent more than the 74 who succumbed to colorectal cancer, the second-biggest killer cancer.
This is despite a lot more people being diagnosed with colorectal cancer – 204 against 149 diagnosed with lung cancer each month.
One reason lung cancer is often fatal in Singapore is that three in four patients are diagnosed at stages 3 or 4, when the cancer has already spread, and cure is difficult. There are usually no symptoms in the early stages of lung cancer.
Professor Lee Pyng, a senior respiratory and critical care consultant at the National University Hospital (NUH), said: “Right now, 68 per cent of lung cancers present as stage 4, where the five-year survival is 20 per cent.”
She is a strong advocate of expanding screening beyond the current recommendation of screening only long-time heavy smokers.
This is because, based on a study by the National Cancer Centre Singapore (NCCS), almost half the lung cancer patients in Singapore have never smoked in their lives.
Prof Lee said: “Low-dose computed tomography (LDCT) screening is the holy grail of detecting lung cancers early in stage 1A to allow curative surgery.”
X-rays, which were used in the past, are not sensitive enough to pick up cancer in the early stages, and have not shown to reduce lung cancer mortality. Radiation from CT scans is of some concern, but LDCT produces just a fraction of the radiation of a normal CT scan. Today, LDCT is the only recommended lung cancer screening in Singapore.
Prof Lee argues that doing so could lead to significant cost savings, given the “exorbitant” cost of chemo and immunotherapy that are typically provided when patients are diagnosed at stage 4. Furthermore, these treatments often prolong survival only “by a mere three months”.
She is not the only one to feel this way. Earlier in 2023, the NCCS launched a large-scale clinical study to see if increased screening can lead to earlier detection.
The study plans to recruit 1,000 participants, both smokers and non-smokers, with a family history of lung cancer.
Dr Gillianne Lai, a medical oncologist at the NCCS, said the study hopes to ”better understand whether LDCT screening for both smokers and non-smokers in Singapore would be beneficial and result in increased rates of early lung cancer detection”.
Lung cancer patients have a 65 per cent chance of living beyond five years – the yardstick used to indicate successful treatment – if the cancer is detected before it spreads beyond the lungs.
Dr Lai said patients with a family history of lung cancer have a higher risk of getting the disease. She said a large-scale clinical study of non-smokers with such family history in Taiwan showed the effectiveness of screening them for lung cancer. Among the 49,508 participants screened, lung cancer was detected in 531 (1.1 per cent), with 85.1 per cent being at very early stages of the disease.
Although the vast majority of lung cancer cases here are picked up late, there has been an increase in the number of patients who discover their cancer while it is still in stage 1.
Dr Lai attributes this to increased awareness, which drives people to go for screening earlier when they experience symptoms, as well as greater interest in screening for the disease, especially among those exposed to second-hand smoke.
She said about half of lung cancers picked up on screening are detected at an early stage when it is more curable, compared with one-fifth who were diagnosed in other ways, such as X-rays and CT scans for other reasons.
Meanwhile, the public healthcare sector has switched from doing single tests to check for biomarkers in patients with advanced lung cancer, to using Next Generation Sequencing (NGS), which is one test that is able to identify many biomarkers that can guide treatment options.
Dr Jens Samol, a senior cancer consultant at Tan Tock Seng Hospital, which made the switch in 2023, said that prior to NGS, there were four separate tests to identify four biomarkers.
But for lung cancer, there are nine biomarkers for which there are now drugs that specifically target them, he said. The identification of biomarkers aids in drug selection, as they would indicate if certain therapies would, or would not, work. This helps to identify the best treatment option for the patient.
Dr Lai said that an NCCS study found that approximately 40 per cent of NGS performed in patients with advanced lung cancer reported potentially actionable alterations, of which 30 per cent were allocated to suitable treatments. The NCCS has been using NGS for some years.
She added: “NGS facilitates the optimal treatment recommendation in a cost-effective setting. NGS also provides the opportunity to identify patients suitable for clinical trials which are evaluating new therapeutic options based on a specific biomarker.”
