Incidence patterns of rare cancer in southeast Asian and western Pacific countries (RARECAREnet Asia project): a study using population-based cancer registry data, 2011-2015

Patumrat Sripan; Siti Norbayah Yusof; Donsuk Pongnikorn; Imjai Chitapanarux; Balqis Bahtiar; Nor Saleha Ibrahim Tamin; Karnchana Daoprasert; Narate Waisri; Young-Joo Won; RuRu Chun-Ju Chiang; Annalisa Trama; Hadrien Charvat; Kriengkrai Srithanaviboonchai; Tomohiro Matsuda

doi:10.1016/j.lansea.2025.100670

Incidence patterns of rare cancer in southeast Asian and western Pacific countries (RARECAREnet Asia project): a study using population-based cancer registry data, 2011-2015

Lancet Reg Health Southeast Asia. 2025 Sep 12:41:100670. doi: 10.1016/j.lansea.2025.100670. eCollection 2025 Oct.

Authors

Affiliations

¹ Research Institute for Health Sciences, Chiang Mai University, Chiang Mai, Thailand.
² National Cancer Institute, Putrajaya, Malaysia.
³ Department of Medical Services, Ministry of Public Health, Nonthaburi, Thailand.
⁴ Chiang Mai Cancer Registry, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
⁵ Division of Radiation Oncology, Department of Radiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
⁶ Ministry of Health, Putrajaya, Malaysia.
⁷ Cancer Registry Unit, Lampang Cancer Hospital, Lampang, Thailand.
⁸ Division of Health Administration, Yonsei University, Wonju, Republic of Korea.
⁹ Taiwan Cancer Registry Center, Institute of Epidemiology and Preventive Medicine College of Public Health, National Taiwan University, Taipei, Taiwan.
¹⁰ Research Department, Fondazione IRCSS, Istituto Nazionale dei Tumouri, Milan, Italy.
¹¹ Faculty of International Liberal Arts, Juntendo University, Tokyo, Japan.
¹² Division of International Health Policy Research, Institute for Cancer Control, National Cancer Center, Tokyo, Japan.

Abstract

Background: In Southeast Asia (SEA), the understanding of most rare cancers is limited, which sometimes leads to delays in diagnosis, treatment, and care. This study aimed to estimate for the first time the incidence of rare cancers in SEA using population-based cancer registry (PBCR) data from the 2011-2015 period.

Methods: This study used data from the nationwide PBCR of Malaysia and two PBCRs in northern Thailand in Chiang Mai and Lampang Cancer registries. The age-standardized incidence rate (ASR) per 100,000 person-year of the rare cancers included in the RARECAREnet list was calculated. All analyses were performed using SEER∗Stat (version 8.3.5). Cancers defined as rare by RARECAREnet in Europe were also rare in Thailand and Malaysia.

Findings: The ASR of some rare cancers in Thailand and Malaysia were greater than that in Japan, Korea, and Taiwan, including some pediatric cancers (pancreatoblastoma and odontogenic malignant tumors) in Malaysia, eye and adnexal cancer, and epithelial tumors of the penis in Thailand. ASR of nasopharyngeal cancer was higher in Thailand and Malaysia than in Japan and Korea but lower compared to Taiwan.

Interpretation: Although most rare cancers were also rare in Thailand and Malaysia, some cancers were not considered rare. However, the incidence of some rare cancers in Thailand and Malaysia were higher than that in Japan, Korea, and Taiwan. To enhance understanding, diagnosis, treatment, and care of rare cancers, reliable epidemiological data needs to be generated under the RARECAREnet Asia project by working with countries in Asia with high-quality PBCRs.

Funding: This study was supported by a UICC Yamagiwa-Yoshida Memorial International Cancer Study Grant (Award/Grant Number: YY/2022-1477) and Government of Japan Ministry of Health Labour and Welfare Grant numbers: 23EA1033, and was partially supported by Chiang Mai University, Thailand.

Keywords: East Asia; Population-based cancer registry; Rare cancer; Southeast Asia.