6 Ways the Covid-19 Pandemic Impacted Cancer Epidemiology in the United States

The COVID-19 pandemic had a significant impact on death rates by demographic groups in many countries, including the United States. These impacts varied depending on factors such as age, sex, race/ethnicity, and underlying health conditions and will have major consequences for cancer epidemiology in the years to come.

Here are some key observations regarding how death rates changed by demographic during the COVID-19 pandemic:

1. Age: COVID-19 had a disproportionately severe impact on older adults. The mortality rate increased significantly with age, with the highest death rates among individuals aged 65 and older. In some cases, long-term care facilities, where many older adults reside, experienced high mortality rates due to outbreaks within those facilities.

2. Sex: Studies showed that males had a slightly higher COVID-19 mortality rate compared to females. The reasons behind this difference are complex and may be related to a combination of biological, behavioral, and healthcare access factors.

3. Race and Ethnicity: Racial and ethnic disparities in COVID-19 mortality were observed in many countries, including the United States. Black, Hispanic, and Indigenous communities often experienced higher death rates compared to white populations. These disparities were linked to social determinants of health, including systemic inequities in access to healthcare, housing, and employment opportunities.

4. Underlying Health Conditions: Individuals with certain underlying health conditions, such as diabetes, obesity, heart disease, and respiratory diseases, were at a higher risk of severe illness and death from COVID-19. The presence of comorbidities increased the likelihood of a severe outcome among those who contracted the virus.

5. Vaccination Status: As COVID-19 vaccines became available, vaccination status played a crucial role in determining who was at risk of severe illness and death. In the beginning of the pandemic, unvaccinated individuals were at a significantly higher risk of death if they contracted the virus compared to those who were fully vaccinated.

6. Healthcare Access: Disparities in healthcare access and quality affected COVID-19 outcomes. Individuals with limited access to healthcare services or those who faced barriers to testing and treatment were at a disadvantage.

It's important to note that the impact of COVID-19 on death rates by demographic groups evolved over time as the pandemic progressed, new variants emerged, and vaccination efforts were implemented.

How did these six factors impact cancer mortality?

According to a study conducted by the CDC in 2022, of cancer deaths with COVID-19 as the underlying cause in 2021:

1. A higher percentage occurred among people who were 65 or older (2.4% or higher) than among those who were 15 to 64 (1.5% to 2.1%). This impacts incidence of cancers that occur later in life, such as lung and bladder cancer.

2. A higher percentage occurred among males (2.6%) than females (2.1%). May have an impact on reproductive cancers such as prostate.

3. A higher percentage occurred among non-Hispanic American Indian and Alaska Native people (3.4%), Hispanic and Latino people (3.2%) compared with members of other racial and ethnic groups (1.5% to 2.5%). A potential consequence of healthcare disparities, cancers common in lower socioeconomic communities include lung, colorectal, and liver cancer.

4. A higher percentage occurred among people with blood cancer (7.4% for leukemia, 7.3% for non-Hodgkin lymphoma, and 5.8% for myeloma deaths) compared with other types of cancer (0.6% for pancreatic cancer, 2.8% for breast cancer, and 3.6% for prostate cancer deaths). This is thought to be because blood cancers directly affect the immune system, leading to more severe Covid-19 infection.

5. Lack of healthcare access significantly reduced reported incidence rates of all cancers, especially lung, melanoma, and prostate cancer, in the US. Lack of early detection and treatment for this cancers will increase their progression and severity, likely leading to higher relative mortality in the coming years.

Percent change (1) in age-standardized, delay-adjusted (2) incidence rates from 2019 to 2020 in top four cancer sites by prevalence, using the November 2022 data submission.

1. Estimates of PC=100 x [rate (2020)/rate (2019)-1] where ratio= rate (2020)/rate (2019) and its confidence intervals are calculated in SEER*Stat. The lower and upper limits of the confidence interval for PC are calculated as (Lower CI – 1) x 100 and (Upper CI – 1) x 100, respectively.

2. Incidence rates were delay-adjusted using the November 2022 submission delay adjustment factors.

3. Rates are per 100,000 population.

4. Rates updated with most recent delay factors on 05/17/2023.

Implications for drug development

The above factors impact addressable patient populations for oncology drugs, depending on indication. To accurately forecast, it is important to answer the following questions:

1. In terms of cancer prevalence, do excess deaths primarily attributed to Covid-19 infection in older demographics outweigh delayed diagnosis and treatment from lack of healthcare access and lifestyle impact during the "Covid years"?

2. Which types of cancer drugs will be needed for this shift in cancer epidemiology?

3. How will Covid-19's impact on different demographics affect resource allocation to address changes in cancer incidence by type?