In a significant milestone for pediatric oncology research, Indian researchers have established one of the country's largest childhood cancer survivorship cohorts, providing new insights into the long-term outcomes of children who have successfully completed cancer treatment.
The findings were published in the journal The Lancet Regional Health – Southeast Asia and describe the development of the Indian Childhood Cancer Survivorship (C2S) cohort, a nationwide initiative designed to understand the long-term health outcomes, treatment exposures, and survivorship experiences of children who have successfully completed cancer treatment across India.
The Childhood Cancer Survivorship (C2S) cohort, developed through collaboration among 20 cancer centres across India, has enrolled 5,419 childhood cancer survivors as of December 2024. Survival data were available for 5,140 participants, making it one of the most comprehensive efforts to understand life after childhood cancer in a low- and middle-income country (LMIC).
The study reported encouraging survival outcomes. Across the entire cohort, the five-year overall survival (OS) rate was 94.5%, while the five-year event-free survival (EFS) rate reached 89.9%. Among survivors who had already completed at least two years of post-treatment follow-up, survival outcomes were even better, with five-year OS and EFS rates of 98.2% and 95.7%, respectively.
Researchers noted that acute leukemia was the most common diagnosis, accounting for 40.9% of cases. Nearly all patients had received chemotherapy (94.7%), while 30.3% underwent surgery and 26.3% received radiotherapy as part of their treatment.
Filling a Major Knowledge Gap
While survival rates for childhood cancers have improved substantially worldwide, most long-term survivorship data come from high-income countries such as the United States, United Kingdom, and Scandinavian nations. Until now, there has been limited information about what happens to survivors in countries with constrained healthcare resources and diverse treatment settings.
The newly established Indian cohort aims to address this gap by systematically tracking treatment exposures, long-term health outcomes, and survivorship patterns across multiple institutions.
According to the investigators, the project serves as a foundation for future research into late effects of cancer treatment, including cardiovascular complications, endocrine disorders, neurocognitive issues, psychosocial challenges, and other health conditions that may emerge years after therapy.
A Unique Perspective from India
Researchers highlighted several features that distinguish the Indian cohort from similar survivor studies conducted in Western countries.
Unlike many international registries that predominantly represent patients treated in highly resourced healthcare systems, the C2S cohort includes survivors from government hospitals, charitable institutions, and private healthcare centres. This provides a broader picture of childhood cancer survivorship across different socio-economic backgrounds.
The study also reflects treatment patterns unique to India. Only 26.3% of survivors received radiotherapy, substantially lower than rates reported in older international cohorts. Investigators suggest this may reflect evolving treatment strategies and efforts to reduce radiation exposure whenever possible.
Another notable observation was the high proportion of leukemia survivors and the relatively low representation of brain tumour survivors. Researchers attribute this difference to referral patterns, treatment practices, and the challenges associated with treating aggressive brain cancers.
Building a Framework for Survivorship Care
The researchers believe the cohort represents more than just a research database. It could serve as the foundation for developing national survivorship guidelines and structured long-term follow-up programmes for childhood cancer survivors.
Cancer survivorship has traditionally received less attention than diagnosis and treatment, particularly in low- and middle-income countries. Many survivors lose contact with healthcare systems after treatment completion, making it difficult to identify and manage late treatment-related complications.
The study demonstrates that large-scale survivorship tracking is feasible even in resource-constrained settings. Investigators noted that collaboration among clinicians, researchers, patient support organizations, and cancer centres was critical to the success of the initiative.
Challenges and Future Directions
Establishing the cohort was not without obstacles. Researchers faced challenges including the COVID-19 pandemic, lack of dedicated funding, limited electronic health records, and difficulties tracking survivors who returned to distant hometowns after treatment.
Despite these barriers, the cohort continues to expand. Ongoing efforts include the introduction of electronic tracking systems, mobile follow-up tools, improved data collection, and collaborations with national health databases.
Experts believe the project could become a model for other low- and middle-income countries seeking to establish childhood cancer survivorship registries. As one of the first prospective survivor cohorts from an LMIC and among the earliest in Asia, the initiative provides a valuable platform for understanding the long-term impact of childhood cancer treatment in real-world settings.
The researchers concluded that the cohort represents an important step toward closing the evidence gap in childhood cancer survivorship and will help generate data needed to improve survivor care, guide healthcare policy, and support future research across India.
