Global burden of cancer pattern in 2020 & prediction to 2040 among older adults

Materials & Methods

Cancer incidence and mortality with future estimates were estimated from the data obtained from the publicly available Global Cancer Observatory - GLOBOCAN 2020 online database (gco.iarc.fr-cancer today, cancer tomorrow and cancer over time). The International Agency for Research on Cancer (IARC) includes data for all cancer sites (ICD-10, C00-C97, except C44) combined, available for 185 countries or territories for 36 different types of cancer by sex and age group^8-10. For continent-wise analysis, data were extracted and reported for Asia, Europe, Northern America, Africa, Latin America and Caribbean, and Oceania (as per IARC-WHO methodology to report cancer statistics based on United Nations Population Division ( https://gco.iarc.fr/today/en/data-sources-methods )^8-10. The study was conducted at the ICMR-Centre for Ageing and Mental Health in Kolkata, India, with approval from the Research Integrity Office (RIO).

Numbers of new cases (incidence) and deaths (mortality) among older persons ≥60 yr, truncated age-standardized incidence & mortality rates (ASR per 100,000) for all cancer sites combined, site-wise, gender and world region-wise were reported, cancer predictions were estimated online using gco.iarc.fr portal^8-10. The truncated ASR was calculated for the age group ≥60 yr by using the world standard population method proposed by Doll et al¹¹. Mortality to incidence (M/I ratio) was calculated by dividing the mortality count by the incidence count and expressed in percentage. All the analysis was done using Microsoft Excel, IBM SPSS v21 (IBM, Armonk, NY, USA) and using IARC-WHO online portal (gco.iarc.fr, cancer today, cancer tomorrow and cancer over time).

Results

Globally in 2020, an estimated 18.1 million persons were newly diagnosed with cancer, and 9.9 million (all cancers excluding non-melanoma skin cancer) died due to cancer in all age groups. Of these, 11.3 million cases, representing 62.3 per cent of all incidence cases and 7.5 million deaths, representing 71.2 per cent of all cancer-related deaths worldwide, were seen in the older age group.

Worldwide, older men accounted for an estimated 56.4 per cent of incidence cases and 56.6 per cent of deaths in 2020. The highest number of new cases and deaths (relative proportion) was seen in Asia, which accounted for 48.9 per cent of all global estimated cancer cases among older adults and 55.7 per cent of all global estimated cancer deaths among older adults. These findings were mainly due to population composition (Table I).

Future burden of cancer among older adults

Overall, the number of new among older adults is expected to rise 75.2 per cent by 2040 in older adults (male and female; Fig. 1) from 11.3 to 19.8 million; an expected 89.2 per cent relative increase in new cases in Asia, 29.7 per cent in Europe, 40.6 per cent in Northern America, 90.6 per cent in Latin America and the Caribbean, 106.1 per cent in Africa and 60.5 per cent in Oceania by 2040)^8-10.

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Fig. 1.

Estimated and projected number of new cases aged 60 yr and older in 2020 and in 2040 (by sex). Source: GLOBOCAN 2020, (gco.iarc.fr).

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The number of deaths among older adults is also expected to increase by 80.2 per cent worldwide (both sexes, from 7.05 to 12.7 million), with 93.7 per cent in Asia, 36.1 per cent in Europe, 97.4 per cent in Latin America and the Caribbean, 57.2 per cent in Northern America, 107.5 per cent in Africa, and 74.6 per cent in Oceania^8-10.

Discussion

Ageing is one of the important non-modifiable biological risk factors for developing cancer¹². Previous studies have shown that the older person has an 11 times higher risk of developing cancer as compared to the younger ones¹³. Older patients are always at an elevated risk of unfavourable outcomes due to co-existing co-morbidity conditions¹⁴. Lower survival rates were seen in older adults as compared to the younger ones due to co-existing co-morbidity conditions and limited treatment options^15,16. An analysis done on American cancer patients revealed that only 65 per cent of those who were 85 years of age or older received surgical treatment¹⁵.

Worldwide, an estimated 62.3 per cent of all incidence cases and 71.2 per cent of all cancer-related deaths worldwide were seen among older adults in 2020; a similar study also reported 66.3 per cent burden¹⁶. Of all global burdens among older adults, about half of the cancer incidence cases were 48.9 per cent and more than half (55.7%) of all cancer-related deaths among older were seen in Asian countries. A previous study on older adults estimated that 55.6 per cent of older cases were from LMICs¹⁷. It was also quite significant to come across from the present study that China alone accounted for 30.5 per cent of all global deaths due to cancer among older adults.

The number of new cancer cases among older adults is expected to rise from 11.3 to 19.8 million (a 75.2% increase). A study done by Pilleron et al¹⁷, also reported a 78 per cent increase in older adult cases worldwide and an expected increase of 84 per cent in LMICs¹⁷.

Lung cancer is estimated as the leading cause of death in both male (90 countries) and female (38 countries) older adults. Mainly higher incidence and mortality rates were seen in Eastern Asia, Central and Southern Europe, Northern America and Australia/ New Zealand. In high-income countries, smoking is the leading cause of lung cancer, and is responsible for about two-thirds of deaths due to lung cancer¹⁸, which can be easily prevented through tobacco policies and regulations.

In China, it is observed that lung cancer among older women has the highest incidence rate in the country, whereas globally breast cancer is the leading global cause of cancer among elderly women. This may be due to second-hand smoke or indoor air pollution, as smoking rates are lower among older Chinese women. The use of smoky coal relative to smokeless coal increased risk by about 99 times among Chinese women¹⁹. Fine particulate matter (PM2.5), an air pollutant, is one of the main factors attributing largely to the proportion of lung cancer deaths apart from smoking, and the PM2.5 ranges from 4.7 per cent in the United States to 20.5 per cent in China²⁰.

While prostate and lung cancer are the leading causes of cancer among older men globally, contrary to that in India, lip and oral cavity cancer are the leading causes. This may be due to the high prevalence of smoking and smokeless tobacco consumption and its prolonged lifetime impact²¹. According to the Global Adult Tobacco Survey (GATS 2016-2017)²², the prevalence of tobacco consumption in India, either smoked or smokeless form, among adults is estimated as 28.6 per cent; in males, it is 42.4 per cent and 14.2 per cent in women. According to the population-based cancer registry report of India tobacco-related cancer in India ranges from 24.5 per cent to 70.4 per cent in males and 10.1 per cent to 46.5 per cent in females²³.

Breast cancer among older adult women is the leading cause of cancer in 145 countries and is the first or second leading cause of mortality in 156 countries. The burden is increasing in countries with demographic and socio-economic transitions like Asian countries, South America and Africa³. Studies have shown that in Asia and African countries, women developed breast cancer at least 10 years earlier than in the most part of Europe or America²⁴. As these countries have younger age groups compared to others, which suggests that in the coming decade as the population will be ageing, the burden will be shifted towards these countries.

The M/I ratio is estimated at 62.3 per cent worldwide, whereas the highest is seen among African countries (76.3%) followed by Asian Countries (71.1%) and the lowest is observed in Northern America (41.6%). The M/I ratio can be considered a comparative indicator of disparities in cancer outcomes and treatment availability^25,26. In lower or lower-medium-income countries, the estimated higher M/I ratio is a matter of concern, and necessary cancer prevention and care plan needs to be adopted. According to the Lancet commission report 2018, 80 per cent of patients living in lower-medium-income countries have very limited or no access to pain and palliative care relief²⁷.

Cancer treatment and care of older patients is challenging for both treating doctors and family members because older adults are more likely to have chronic health conditions, higher treatment-related toxicities and complications, etc^28,29. The increased burden among older adults will challenge the worldwide strained healthcare systems, especially in developing countries and bring economic costs to the countries.

As the global burden of cancer is increasing, mainly among older adults due to the interplay between ageing and other risk factors, the role of geriatric oncology has become immense³⁰. The incidence and mortality pattern is diverse geographically; a local comprehensive geriatric cancer control strategy is therefore the need of the hour. Geriatric oncology attempts to ensure overall improvement in functional and nutritional status, social support, cognition, and psychosocial functioning of elderly cancer patients.

Geriatric oncology has paramount importance, especially in lower- medium- income countries like India, where it is seen that 98 per cent of older patients have at least one deficit, of which co-morbidities (79%) is very common followed by fatigue (77%), nutritional deficiency (65%), functional deficiency and falls (52%) and psychological issues (32%)³¹. Psychological aspects of cancer patients are often neglected. Studies showed about 30-40 per cent of older aged cancer patients needed psychological counselling. However, most countries do not integrate psychological counselling into their treatment plan³². Along with psychological counselling, social support and nutrition counselling are to be provided for better outcomes³³. Geriatric assessment and appropriate interventions are crucial in improving the overall health and wellbeing. However, limited utilization of this is observed among lower or lower-medium-income countries.

Due to the non-inclusion of elderly adults in randomized trials, there was a lack of evidence on risk and benefits. For example, due to restrictions on breast cancer screening for elderly females above 75 years, the risk-benefit assessment could not be done, ultimately impacting the treatment outcomes^34,35. Studies also supported the necessity of stoppage of smoking or alcohol cessation, weight management, and social support for overall health benefits for older adults^36,37.

The limitations of our study should be taken into consideration when interpreting the results. Firstly, not all countries have the same quality of data, particularly those where there isn’t a high-quality national mortality register, which may affect the estimations. Secondly, country-specific reasons of death were not available, to associate causes with the mortality rates. Moreover, in the GLOBOCAN 2020 online database, for some countries, data were not available for incidence and mortality estimates, so under- or over-estimation cannot be ruled out. However, despite the limitations IARC-WHO is a trustworthy worldwide data source for to comprehend the pattern of cancer statistics.

Overall, with disparity, a 2-3 fold increase in cancer incidence (75.2% increase) and mortality (an 82.8% increase) is estimated among older adults by 2040. A comprehensive geriatric treatment protocol needs to be adopted as per local situation, along with a global action plan to deal with the growing cancer burden in older adults.