Cancer: What’s My Risk? A Look At Critical Illnesses

We all know someone who has had cancer. There is no doubt that cancer is one critical illness which everyone dreads. Whether it is the fact that cancer accounts for more than a quarter of all deaths in Singapore, or that cancer rates are increasing among younger people, or recent news of prominent people passing from cancer, there seems to be no escaping the clutches of the critical illness of cancer. So, what’s my risk of cancer?

A common cancer statistic is that we have a one in four, or 25% chance of developing cancer in our lifetimes. This sound high, until we also realise that we have a 100% chance of dying in our lifetime as well. Also, this statistic covers all types of cancers, ranging from the Stage 1 and Stage 2 cancers which are confined to a tumour in an organ, and to the Stage 3 and Stage 4 cancers, which involve adjacent organs, and/or may have spread to elsewhere in the body. Often, what we try to insure ourselves against through critical illness insurance are only restricted to Stage 3 and Stage 4 cancers. So let’s take a deeper look at what is the risk of developing a critical illness cancer.

Critical Illness: What’s My Risk of Cancer?

Understanding Cancer Statistics

Fortunately for us, cancer diagnoses and hence risk has been well documented in Singapore, thanks to the National Registry of Diseases Office (NRDO). Every couple of years or so, they publish an annual report about the most common critical illnesses in Singapore – cancer, heart attacks and stroke. And these publications contain a wealth of information which can help dispel some myths about the risk of cancer.

We’ll start off by looking at the infographics and statistics published by the NRDO on cancer in their Cancer Register 2020 Annual Report. Here are a few snapshots about the trends in cancer in Singapore over time:

Cancer Incidence in Singapore over Time (1968 – 2020)

Source: Cancer Register 2020 Annual Report

In terms of cancer incidence, or diagnosis, the number of cases has gone up significantly over time, both in absolute terms (a 6X increase), and also as a percentage of the population (a 25% increase). But the curious thing here is that the median age at diagnosis has also gone up. Can it be that the increasing number of cancer cases we read about are mainly due to the ageing population, since cancer mainly affects older people? It could well be!

Cancer Mortality in Singapore over Time (1968 – 2020)

Source: Cancer Register 2020 Annual Report

In terms of deaths from cancer though, we are better off, with the mortality rate going down by 20% over time, even though the absolute number of deaths has ballooned, simply due to the ageing of the population. Better health care and earlier detection of cancer has really paid off!

One of the things which makes it hard to interpret cancer statistics (and other disease statistics too) is that they are often expressed as Age Standardised Incidence Rates (ASIR), or Age Standardised Mortality Rates (ASMR). This simply means that the cancer incidence or mortality rates of each age group are weighted by the proportion of that age group in the population to give an overall picture for the current population. Which means that this will naturally tend to go up over time because there are more old people in the population in recent years. And not because the disease strikes more often! We can see this in the chart below from the Cancer Annual Report 2020:

Cancer Trends in Singapore (1970 – 2020)

Source: Cancer Register 2020 Annual Report

A couple of interesting things jump out from this chart above. Firstly, thanks to advances in medical science, the death rate from cancer has been dropping over time since 1980. Remember that this has been happening even before the expensive, cutting edge treatments for cancer which are not on the cancer drug list were introduced! And this is even after taking into account the ageing population (these are age standardised measures, remember?). So that is wonderful news. Even though science cannot eliminate cancer right now, it is becoming less and less of a threat over time.

Secondly, there are distinct differences between cancer on men and in women. For the men, surprisingly, even as the population ages, and there are more efforts to detect cancer early (e.g. colonoscopies being encouraged for people above 50 years of age to detect colon cancer), the incidence rate of cancer in men has basically stayed the same over time. This may have a great deal to do with reduction in smoking over time, which is largely a male habit.

But for the women, it is a case where cancer incidence rates have been rising over time! Why is this so? At the same time though, the cancer mortality rates for women have been going down! Again, this may have to do with earlier detection of breast cancer, the most common cancer among younger women. And since breast cancer tends to be detected in Stage 1 or 2, meaning that it is curable, the reduction in death rates follow.

Hence, the message in these statistics is that the risk of cancer has been dropping over time. In fact, it is now the lowest that it has ever been for a very long time. And even more reassuring, the risk for the young people (say, below the age of 50) has been dropping even more rapidly. This is even with the greater emphasis now on early detection through testing, especially in the last 20 years:

Age of Cancer Diagnosis for Males (1968 – 2020)

Source: Cancer Register 2020 Annual Report

Age of Cancer Diagnosis for Females (1968 – 2020)

Source: Cancer Register 2020 Annual Report

For both the men and the women, the reason why there are a lot more cancer cases now than in the past is simply because there are far more elderly people around now. For the young, the unambiguous finding is that the risk of cancer has been decreasingly, and at a faster rate than ever since 2003. So, even if we scare ourselves silly about developing cancer while young, in truth, it is becoming less of a health risk for us.

Risk of critical cancer

While it may be reassuring to know that the overall trends in cancer risks are declining, what matters to an individual is the risk to himself or herself. Incidence, or case rates per 100,000 people may be hard to interpret if we do not have a benchmark to anchor that particular risk to. So what we do here in this section is to take the raw incidence rates by age groups (i.e. 30-39 years of age, 40-49 years, 50-59 years, and so on) and compare them to a risk which may be a little more familiar – the risk of death from any cause. In the following charts, we use the age group specific cancer incidence rates (per year) in 2018-2020 from the NRDO, and compare them with the average mortality rates from the Life Tables in 2020.

Cancer Risk for Men, compared to Risk of Death from Any Cause (2018-2020)

Cancer Risk for Women, compared to Risk of Death from Any Cause (2018-2020)

Let’s start with the men first. From the first chart, it appears that the risk of being diagnosed with any form of cancer is about on par with the risk of death from any cause, until about the age of 70 onwards, when the risk of death overtakes the risk of cancer (even though the median age for cancer diagnosis is 66). It turns out that having cancer in the 70’s or 80’s is not really the biggest concern here, as the elderly have a lot more to worry about!

But overall, especially for the young, the message is quite clear. The risk of cancer is roughly the same as the risk of death, and this is quite low for the young, i.e. those under 50 years old. This risk then starts to creep up, but even then, it is a 1% of less risk until the age of 70, on average.

What about for the women? For them, the risk of cancer until the age of 70 is higher than the risk of death from any cause, quite unlike the men! This is likely to be due to the most common cancer for women being breast cancer, and this is something which tends to be detected in younger women.

However, note that breast cancer tends to be detected in the early stages, and this means that the chance of survival is really quite high. Also, if we look more closely at the scales of y-axis of the two charts, if shows that women on the whole tend to have a risk of death and cancer only about two thirds that of the men. So no matter how high or scary that cancer risk looks for the women, it is still some way lower than the cancer risk for men. For example, between the age of 50 to 70, the cancer risk for women is between 0.5% to less than 1% per year, which is comparable to that for the men and sometimes lesser.

But what we really worry about is not just a cancer diagnosis, but a critical cancer diagnosis, which is a cancer in Stage 3 or Stage 4. This is the stage when the cancerous tumour may have affected another organ in addition to the original one it starting growing in, and may all have spread elsewhere in the body through the blood (very common for liver, lung and pancreatic cancer). To work out the risk of critical cancer, we took the proportion of Stage 3 and Stage 4 cancer diagnoses for the most common cancers for men and women, and applied it to the raw cancer risk rates shown earlier. The most common cancers for men and women are:

Most common cancers

Men	Women
Colon	Breast
Lung	Colon
Prostate	Lung

Source: Cancer Register 2020 Annual Report

And here is what critical cancer risk looks like:

Critical Cancer Risk for Men, compared to Risk of Death from Any Cause (2018-2020)

Critical Cancer Risk for Women, compared to Risk of Death from Any Cause (2018-2020)

Compared to the earlier charts of the cancer risk to both men and women, it is clear from the critical cancer charts that the risk of being diagnosed with Stage 3 or Stage 4 cancer is significantly lower. During the high risk years from age 60 to 80, the critical cancer risk is between half to two-thirds the risk of death from any cause. And beyond the age of 80, critical cancer risk is only about a third of mortality risk.

Hence, in a nutshell, what the statistics on cancer in Singapore are showing us is that the risk of a Stage 3 or Stage 4 cancer diagnosis is still lower than the risk of death. And this risk tends to be pretty low below the age of 50, and only starts going up after that.

Conclusions

Cancer is often regarded as the scourge of our times. Our media feeds are often inundated with stories of celebrities and other prominent people who have fought cancer, and sometime lost. Our personal lives are often intertwined with friends and family who have experienced the same. But what is the real risk of cancer?

This is a question that only statistics can answer. And we have lots of it from the National Registry of Diseases Office in Singapore. And what the statistics show is that:

Cancer mainly afflicts older people, with the median age at diagnosis being 66. There seems to be a lot of cancer nowadays, but this is because people are living longer, well past the age of 66
While cancer is the leading cause of death in Singapore, the mortality rate for cancer has been dropping since the 1980s, and continues to do so
For the men, despite an ageing population and efforts at the early detection of cancer, cancer risks have not increased since 1990
For women, the cancer risks have increased over time, but mortality rates have not, so the increased detection of cancer have been mainly early stage cancers, with are less deadly
Overall, for both men and women, the risk of being diagnosed with critical cancer (i.e. Stage 3 or 4) is still low, lower than the mortality risk from any cause

Next, we will take a look at heart attacks and strokes!