Cancer prevalence: how many people are living with and beyond cancer in Canada?

CCS host: Hi and welcome to the Canadian Cancer Society’s Expert Angle webinar series. This webinar is titled Cancer prevalence: how many people are living with and beyond cancer in Canada? Today's guest speaker is Jennifer Gillis, the senior manager of surveillance for the Canadian Cancer Society. Dr Gillis works closely with the Canadian Cancer Statistics Advisory Committee to develop the Canadian Cancer Statistics report, which you will hear more about. Thank you all for joining us today. If you have any questions for our speaker today, please click the speech bubble on the top left of your screen to submit your question. Our speaker or an information specialist will get back to you as soon as possible. Dr Gillis, I will now turn this webinar over to you.

Jennifer Gillis: Great. Thank you. Hi, I'm Jennifer and I'm excited to be here to present on cancer prevalence in Canada. This webinar has been designed to help you learn what cancer prevalence is and why it's an important measure, how it is different from cancer incidence and what prevalence is able to tell us. And finally, what we know about cancer prevalence in Canada today from the latest prevalence data. To do this, we'll be presenting findings from Canadian Cancer Statistics: A 2022 special report on cancer prevalence. Visit cancer.ca/statistics to find the full report. This report was developed by the Canadian Cancer Statistics Advisory Committee in collaboration with the Canadian Cancer Society, Statistics Canada and the Public Health Agency of Canada, with data provided from the provincial and territorial cancer registries and Canadian Vital Statistics. The 2022 Advisory Committee was co-chaired by Dr Darren Brenner from the University of Calgary and Abbey Poirier from the Canadian Cancer Society. The analysis presented in the report and this webinar were conducted by Statistics Canada and the Canadian Partnership Against Cancer. This work would not be possible without the dedicated support and expertise provided by the members of the committee, the analysts at Statistics Canada and the Canadian Partnership Against Cancer, and our reviewers. So thank you all.

I want to start with some key take-home messages to guide the webinar and our learning. Cancer prevalence is a measure that tells us how many people are living with or beyond a cancer diagnosis. It is an important measure of the impact of cancer on people in Canada, our communities and society more broadly. It helps inform healthcare delivery and planning to meet the needs of those affected by cancer. Over 1.5 million people in Canada are living with or beyond cancer, up to 25 years after a cancer diagnosis. Cancer prevalence is rising. The number of people living with or beyond cancer in Canada continues to grow, and breast, prostate and colorectal cancer are the most prevalent. Combined, they count . . . account for about half of all prevalent cancers.

And to ground the conversation today and remind us that this 1.5 million estimate represents individuals affected by cancer, we have Reg. In 2014, Reg was diagnosed with prostate cancer. Living over 150 kilometres away from the nearest hospital in rural Nova Scotia, Reg heard about the Lodge that Gives in Halifax. He was able to benefit from receiving a comfortable home away from home during his treatment. After his diagnosis, Reg was committed to living a healthy lifestyle and lost a significant amount of weight through exercise and healthy eating. He considers himself a cancer thriver and continues to keep a positive attitude and healthy lifestyle. So now we'll hear directly from Reg about his cancer experience.

Reg: Hi, I'm Reginald Dane Berringer, and I'm a prostate cancer survivor. Cancer was quite prevalent in my family, even growing up. My mother was diagnosed with breast cancer early, in my late teens, and after a mastectomy, survived to live to be 94. My older sister lost a kidney to kidney cancer and she's still alive now, she's in her, in her 70s. And, um, my other sister had pancreatic cancer, but it was not found in time and she did not survive. My father was the only one of our family that didn't have cancer, and he survived into his late 80s.

I have to say, there's nothing . . . It's not even describable when you hear those 3 words from your family doctor. And that is that you have cancer. It’s an indescribable feeling, even myself, who had had many family members who had cancer, and experienced it with them and supported them. It's nothing like when those words land in your brain. It's like you feel like your body has turned against you, that, that something's gone wrong. And I have to say: I was a policeman for 30 years. I was in the military. I've been shot at. I've jumped out of airplanes 3 times. I had 3 motorcycle accidents that, it's a miracle I wasn't killed. But none of that prepared me for being told that I had cancer.

I went through 3 types of treatment. I went through surgery, had my prostate removed, and that was followed by 6 1/2 weeks of radiation therapy where I stayed at the Lodge that Gives which is a, a place to stay when you're having cancer treatment, that's funded by the Canadian Cancer Society, and they became my family to support me through my radiation treatment. And then I was, went through almost a year of androgen deprivation therapy which took all the, took all the testosterone in my body and that, that was a hoot and a holler, I’ll tell you that. My wife said now I know what night sweats are.

So, that's my story in a nutshell and what I wanna stress is: that's thousands of Canadian stories. There's thousands of Canadians right now going through that same story. And if you have any dealings with the Canadian Cancer Society, I hope that you support them as they have supported and helped me through my treatment and my recovery. I’m, I'm 4 and . . . 6 months away from being declared cancer-free. And it's been a long journey, but it's a journey, and a lot of Canadians are unfortunately sharing. And that's my story. Thank you very much.

Gillis: Thank you, Reg. Many of you may be wondering, what is cancer prevalence? Prevalence provides an estimate of how many people have been diagnosed with the disease in the past and are still alive on a specific date. Therefore, cancer prevalence can really be thought of as the number of people living with or beyond cancer. This is person-based prevalence. However, since some people may be diagnosed with multiple types of cancer, tumour-based prevalence can help be helpful to estimate the number of cancer cases diagnosed among individuals living with or beyond cancer. So to recap, person-based prevalence refers to the number of individuals living with or beyond cancer on a specified date. We call this the index date. Tumour-based prevalence refers to the number of cancer cases diagnosed among individuals living with or beyond cancer on a specified date or the index date, as we say.

That was the what and now to the how. How is cancer prevalence calculated? Prevalence estimates include individuals from those newly diagnosed with cancer to those who have survived cancer and all those at various points in their cancer experience. Since we need to know who has been diagnosed in the past and is still alive, we calculate cancer prevalence at a specific point in time. As I mentioned, this is the index date among the people alive. On the index see, we count how many people or cancer cases have been diagnosed over a duration of time prior to that date. This is the prevalence duration. Prevalence durations can be considered short term, often 2- or 5-year durations or long term like the example below with a 25-year duration. In this case the index date is January 1st, 2018, so we count the number of people who are alive on this date who had been diagnosed with cancer anytime in the previous 25 years.

Here's an example that might make cancer prevalence more understandable. Imagine there are 100 people living on a small island on January 1st, 2018. Four of these people had been diagnosed with cancer in the past. One of them had been diagnosed long ago. 23 years ago, to be exact. Another was diagnosed about 12 years ago. And the last 2 were diagnosed more recently, one of them 4 years ago and the other almost 2 years ago. So on this island, 4 people were living with or beyond cancer at the beginning of 2018. This is the 25-year prevalence estimate. We can turn this into a proportion of the population who are living with or beyond cancer. In this case the 25-year prevalence proportion is 4 per 100 people since there are 100 people on the island. This translates into one in 25 people living with or beyond cancer on the island at the beginning of 2018. I used 25-year prevalence as the example because the report provides 25-year cancer prevalence, the longest duration we have been able to calculate in Canada.

So at the beginning of 2018, 1.5 million people in Canada were living with or beyond a cancer diagnosis. Almost 1.7 million cancer cases had been diagnosed in people still alive up to 25 years after their cancer diagnosis. About 60% had been diagnosed in between 5 and 25 years prior, highlighting the high number of people living long-term with or beyond a cancer diagnosis. And as more people are diagnosed with and survive cancer, the number is expected to be higher today. And this is because prevalence is rising for the 2-, 5- and 10-year prevalence durations. The number of prevalent cancers per 100,000 people has increased overtime as shown in the figure. The bottom line is 2-year, the middle 5-year and the top line is 10-year prevalence. As we see, it is increasing overtime. This growth is likely a function of an aging population and more people being diagnosed with cancer, as well as improved survival across several cancer types resulting from cancer screening and improved treatments and cancer care.

As I mentioned in the key messages at the beginning of the webinar, cancer prevalence is an important measure of the impact of cancer on individuals, families, communities and society. Each person's cancer experience is different. The complexity of their needs can vary by cancer type and severity. However, generally people diagnosed with cancer will require a higher level of support and resources early in their care. During the transition to recovery and survivorship as well as through end-of-life care. As both survival for most cancers and the number of long-term survivors from cancer increase, resources will be needed to ensure optimal quality of life in the post treatment and survivorship periods. Therefore, knowing how many people are living with or beyond cancer is important for healthcare planning and delivery. Estimates of prevalence by different prevalence durations can help inform health and supportive care planning and delivery. In the first couple years after a diagnosis, individuals are likely receiving primary treatment or recovering from its effects. In the third to fifth year, people typically require close clinical follow-up for recurrence, meaning the cancer coming back or another primary cancer diagnosis, as well as receiving supportive care. People alive more than 5 years after a diagnosis have likely completed their primary treatment, but some may still need clinical monitoring and supportive care. Prevalence by duration is instrumental in estimating the short and long-term needs for cancer care and resource allocation, including healthcare costs.

To recap, short-term prevalence estimates the number of people who have been diagnosed with cancer more recently, usually within 2 to 5 years of the index date and are still alive. It helps jurisdictions plan resource allocation for early cancer care and supportive services. Whereas long-term prevalent estimates the number of people diagnosed with cancer longer ago, usually more than 5 years prior to the index state and are still alive, it helps inform. Survivorship planning, which is health care and services designed to support the unique needs of people living beyond a cancer diagnosis. Overall, the 25-year tumour-based prevalence was almost 1.7 million cancer cases, but we can examine how many were diagnosed more recently, so short term prevalence and those diagnosed longer ago long-term prevalence. Of the 1.7 million cancer cases, 18% were diagnosed in the previous 2 years and 21% within the previous 2 to 5 years, while the majority 61% were diagnosed within the previous 5 to 25 years. The distribution of cancer cases across prevalence durations may be different for different cancer types, and this is because cancer prevalence is impacted both by both incidents and survival, which also differ by cancer types.

So incidence and survival and prevalence -- oh my! You may have heard of cancer incidence. This is the number of cancer cases. Incidence measures how many people or cases of a disease are newly diagnosed in a population in a given year. So, cancer incidence rates are typically reported as the number of new cases for every 100,000 people in the population in a year. Survival gives a sense of the percentage of people expected to survive their cancer diagnosis and is calculated among those diagnosed with cancer. Survival differs by cancer type. And finally, prevalence, as I mentioned, is impacted by both incidents, so the number of new cases and survival. Someone must be diagnosed with cancer and survive to the index to be counted in the prevalence estimate. So a cancer type that has high incidence but low survival may be less prevalent in the living population than a cancer with lower incidence but better survival.

It might help to see some examples. Breast, lung, prostate and colorectal are the most commonly diagnosed cancers. They have the highest incidence. Breast and prostate have high observed survival compared to colorectal and particularly lung cancer. Therefore, we see a higher number of prevalent cases of breast and prostate compared to colorectal and lung. We also see a high proportion of the prevalent cases for breast and prostate were diagnosed over 5 years before the index date. This is shown in yellow. Due to the lower survival for colorectal cancer, the proportion of cancer cases diagnosed over 5 years before the index date is lower. This is even more striking for lung cancer cases due to its low survival. The report also provides cancer prevalence estimates by cancer type more broadly beyond the 4 most commonly diagnosed, and what was found is that combined breast, prostate and colorectal cancers account for nearly half of all prevalent cancers. Other prevalent diagnoses include melanoma of the skin, thyroid cancer, urinary bladder cancer, Non-Hodgkin lymphoma, uterine cancer and lung cancer.

The report also provides cancer prevalence estimates for across Canada. The number of people living with or beyond cancer varies across Canada due to differences in population sizes of our regions. Prevalence proportions were generally higher in Atlantic provinces, mirroring what we see with cancer incidence. Prevalence proportions do not adjust for differences in the ages of the populations, as these measures are really meant to show us the natural differences in disease burden to support regional planning. Therefore, we also observe lower prevalence proportions for younger jurisdictions such as Alberta and the territories. And short term 5-year prevalence was higher among those living in rural areas compared to those living in urban areas as shown in the figure. This pattern was seen for all cancers combined and among the 4 most commonly diagnosed cancers, although it was less pronounced for breast. The higher proportion in rural areas is likely driven by age differences, as people in rural areas are typically older than those living in urban areas in Canada. But other factors beyond age may also impact cancer prevalence, including access to healthcare.

I now want to end where we started with some of the key take-home messages from this webinar. Cancer prevalence is a measure that tells us how many people are living with or beyond a cancer diagnosis. It is important measure of the impact of cancer on people in Canada, our communities and society more broadly. It helps inform healthcare delivery and planning to meet the needs of those affected by cancer. Over 1.5 million people in Canada are living with or beyond cancer up to 25 years after a cancer diagnosis. Cancer prevalence is rising. The number of people living with or beyond cancer in Canada continues to grow. And breast, prostate and colorectal cancer are the most prevalent. Combined, they account for about half of all prevalent cancers.

As mentioned at the beginning of this webinar, this report and its findings would not be possible without the dedicated expertise and support of all the individuals listed on this slide. This includes all members of the Canadian Cancer Statistics Advisory Committee, the analysts from Statistics Canada and the public, sorry, and the Canadian Partnership Against Cancer and our peer reviewers. Many thanks for your support on this important work. Finally, to our viewers, thank you for joining this webinar. Please visit cancer.ca/statistics for more information or to download the full report. Thank you.

CCS host: Thank you so much, Dr Gillis, for sharing key findings from the recent Canadian Cancer Statistics report and explaining why cancer prevalence is an important measure of the impact of cancer on individuals, families, communities and society. We appreciate your time and expertise. The Canadian Cancer Society is dedicated to supporting people affected by cancer at all stages of the cancer experience. To help us make sure we are providing the information you need most, please take a few minutes to fill in our short survey about this webinar and what topics you would like us to cover in the future.

Finally, we would like to make you aware of the Canadian Cancer Society's free information and support services that you can access online or over the phone from the comfort of your home. These services are confidential, and many are available in multiple languages. Our Cancer Information Helpline can answer your questions about diagnostic tests, treatments, side effects, clinical trials, coping with cancer, COVID-19 risk resources and many other related topics. Call 1-888-939-3333 or e-mail info@cancer.ca. Our online community, CancerConnection.ca, helps people who have cancer, cancer survivors and caregivers share their experiences and build supportive relationships. For any other cancer-related information, please visit our website cancer.ca. You can also live chat with one of our information specialists who can answer your questions and connect you with additional resources.

Thank you again to our speaker today for joining us and sharing their expertise. This now concludes today's presentation and on behalf of the Canadian Cancer Society, we wish you well.