Epidemiology

Global

Geographical variation, environmental exposures and socioeconomic factors all have an impact on the incidence and mortality of cancer, which is a significant global public health concern [16]. According to International Agency for Research on Cancer (IARC) estimates for 2022, cancer accounted for approximately 9.7 million deaths and 19.98 million new cases worldwide, including non-melanoma skin cancers. Projections suggest that global cancer incidence may reach 35 million cases annually by 2050, reflecting demographic growth and population aging [4].

Among major cancer sites, lung and breast cancers remain the most frequently diagnosed globally, while HNC constitutes a significant proportion of cases, particularly in low and middle-income countries. Based on the data available from the WHO (2022) occurrence of cancer in major sites is shown in Fig. 1.

Fig. 1: Percentage distribution of cancer incidence in India, Asia, and the World as reported in GLOBOCAN, 2022

Asia

Asia is the most densely and diversely populated region, representing nearly 60% of the global population. Improvements in the healthcare system and continued socioeconomic growth have contributed to a significant increase in life expectancy in Asia. In 2022, an estimated 9.8 million incident cancer cases and 5.4 million deaths occurred across Asia, constituting nearly 50% of the global burden, thereby signalling a major public health threat in the region. China, India, and Japan collectively account for the highest cancer incidence and mortality across the Asian continent [1]. In Asia (2022), lung cancer ranks first, followed by breast cancer, colorectal cancer, stomach cancer, and HNC as the most commonly occurring malignancies.

As per the WHO (2022) data of Asia, it is noticed that the incidence rate (Fig. 2a) and mortality rate (Fig. 2b) of HNCs are significantly higher in India compared to other Asian countries. The rise in HNCs in Asia is mainly due to the widespread use of tobacco smoking and chewing accounts for up to 80% of all head and neck squamous cell carcinoma (HNSCC) cases [17]. Cultural habits like BQ, pan, gutkha, supari consumption, lack of oral hygiene, unawareness of early symptoms, poor screening, late-stage diagnosis, and limited access to specialized cancer care, especially in rural areas, including India’s largest population, make the countries a hotspot for HNC burden. Socio-economic factors, such as poverty, poor education, and high treatment costs, also contribute to delays in diagnosis and treatment. Additionally, exposure to environmental and occupational pollutants further increases risk, making HNC a major public health concern in Asia.

Fig. 2: a Map showing estimated HNC incidence in Asia in 2022 (GLOBOCAN 2022). b Map showing estimated HNC mortality in Asia, in 2022 (GLOBOCAN 2022). (https://www.mapchart.net/asia.html)

India

Cancer occurrence is not homogeneous in India, but it is an increasing health challenge in the country, impacting lives across diverse socio-economic and geographies of the country [18]. In a population of 1.46 billion, nearly 1.3 million individuals develop cancer every year. Roughly one in every 10 Indians will develop cancer in their lifetime and this proportion may rise with improved detection and diagnosis. Mathur et al. [19] report that there were an estimated 13.9 million cancer cases in the country in 2020. India ranked third after China and the USA [20]. Among the top five cancers in the country, HNC (27.9%) was found to be the highest, followed by breast (13.6%), cervix uteri (9%), and lung (5.8%), this is diagrammatically shown in the Fig. 3. The cancer rise in India can be attributed to several determinants, including rapid urbanization, aging demographics, sedentary behaviour, and the widespread adoption of nutritionally poor diets. Moreover, the escalating exposure to both indoor and outdoor air pollution are becoming a major area of concern [21, 22]. The escalating rate of cancer diagnosis in India presents a formidable challenge to public health.

Fig. 3: Percentage distribution of cancer incidence in India as reported in GLOBOCAN, 2022