Epidemiology of rare cancers in India and South Asian countries - remembering the forgotten

Sharada Mailankody; Jyoti Bajpai; Atul Budukh; Rajaraman Swaminathan; Rajesh Dikshit; Meghnath Dhimal; Suraj Perera; Ugyen Tshomo; Sonali Bagal; Mahadev Bhise; Pankaj Chaturvedi; Shripad D Banavali; Sudeep Gupta; Rajendra A Badwe; Annalisa Trama

doi:10.1016/j.lansea.2023.100168

Epidemiology of rare cancers in India and South Asian countries - remembering the forgotten

Lancet Reg Health Southeast Asia. 2023 Feb 27:12:100168. doi: 10.1016/j.lansea.2023.100168. eCollection 2023 May.

Authors

Affiliations

¹ Department of Medical Oncology, Kasturba Medical College, Manipal, Manipal Academy of Higher Education, Manipal, Karnataka, India.
² Department of Medical Oncology, Tata Memorial Center, Homi Bhabha National Institute, Mumbai, India.
³ Centre for Cancer Epidemiology, Tata Memorial Centre, Homi Bhabha National Institute, Mumbai, India.
⁴ Department of Epidemiology, Biostatistics and Cancer Registry, Cancer Institute (WIA), Chennai, India.
⁵ Nepal Health Research Council, Kathmandu, Nepal.
⁶ National Cancer Registry Program, Colombo, Sri Lanka.
⁷ Department of Gynecology, Jigme Dorji Wangchuck National Referral Hospital (JDWNRH), Thimphu, Bhutan.
⁸ Principal Investigator of Cancer Registry, Thimphu, Bhutan.
⁹ Department of Surgical Oncology, Tata Memorial Centre, Homi Bhabha National Institute, Mumbai, India.
¹⁰ Department of Preventive and Predictive Medicine, Fondazione IRCSS, Milan, Italy.

Abstract

Background: Rare cancers (RCs) are challenging to manage and are "forgotten cancers" though they collectively constitute a significant proportion of all cancers (∼20%). As a first step towards streamlining care, there is an unmet need to map the epidemiology of RCs in South Asian Association for Regional Collaboration (SAARC) countries.

Methods: The authors collected data from 30 Population-Based Cancer Registries (PBCR) of India and the published national registries of Nepal, Bhutan and Sri Lanka (SL) and compared them with the standard RARECAREnet RC list.

Findings: With the standard definition of crude incidence rates (CR) ≤6/100,0000 per population, 67.5%, 68.3%, 62.3% and 37% of all incident cancers qualify as RCs in India, Bhutan, Nepal and SL, respectively. An arbitrary cut-off CR ≤3 appears more appropriate with 43%, 39.5%, 51.8% and 17.2% of cancers identified as RCs, respectively, due to the lower cancer incidence.There are similarities and notable differences between the RC lists of the SAARC region with that of the European RC list. Oral cavity cancers are rare in Europe, while pancreas, rectum, urinary bladder and melanomas are common. In addition, uterine, colon and prostatic cancers are rare in India, Nepal and Bhutan. In SL, thyroid cancer is common. There are gender-related and regional differences in RC trends in the SAARC countries.

Interpretation: There is an unmet need in SAARC nations to capture epidemiological nuances in rare cancers. Understanding the unique issues in the developing world may guide policymakers to adopt appropriate measures to improve RC care and tailor public health interventions.

Funding: None.

Keywords: Bhutan; Epidemiology; Incidence; India; Nepal; Rare cancer list; Rare cancers; South Asian Association for Regional Cooperation (SAARC) countries; Sri Lanka.