FOR IMMEDIATE RELEASE
ST. JUDE CHILDREN’S RESEARCH HOSPITAL, MEMPHIS, TN – A groundbreaking study published today in The Lancet Oncology has fundamentally reshaped our understanding of the factors contributing to secondary cancers in survivors of childhood cancer. Scientists at St. Jude Children’s Research Hospital have for the first time quantified the proportional contributions of life-saving cancer treatments and individual genetic predispositions to the risk of developing a second malignancy – a primary cause of mortality for long-term survivors. The findings reveal that a survivor’s genetic makeup can be as significant, or even more significant, than chemotherapy exposure in determining this critical risk, challenging conventional wisdom and paving the way for more personalized and proactive surveillance strategies.
This landmark research, leveraging the unparalleled datasets of the St. Jude Lifetime Cohort Study (St. Jude LIFE) and the Childhood Cancer Survivor Study (CCSS) – two of the world’s premier longitudinal studies housed at St. Jude – provides a critical roadmap for physicians. It underscores the necessity for clinicians caring for this vulnerable population to consider not only the historical record of aggressive pediatric treatments but also the intricate tapestry of a patient’s inherited genetic vulnerabilities.
The Enduring Challenge: Secondary Cancers in a Growing Survivor Population
The remarkable advancements in pediatric oncology over the past several decades have transformed childhood cancer from a near-certain death sentence into a largely curable disease. Survival rates for many childhood cancers now exceed 80%, leading to a burgeoning population of millions of adult survivors worldwide. This triumph, however, has brought into sharper focus a new and profound challenge: the long-term adverse effects of aggressive, life-saving therapies, chief among them the development of secondary cancers.
For many years, the primary focus of long-term survivor care revolved around the known late effects of treatment – radiation-induced toxicities, cardiotoxicity from certain chemotherapies, and the increased risk of subsequent malignancies. These secondary cancers are not merely a theoretical concern; they represent the leading cause of mortality among long-term survivors, often occurring decades after the initial diagnosis and cure. Understanding the precise interplay of factors driving this risk has been a critical unmet need, hindering the development of truly individualized surveillance and prevention strategies.
A Landmark Study Unravels Complexities with Unprecedented Data
Addressing this profound knowledge gap required an extraordinary confluence of data and scientific expertise. The St. Jude study, led by corresponding author Yadav Sapkota, PhD, of the St. Jude Department of Epidemiology and Cancer Control, achieved this by analyzing information from over 10,000 survivors enrolled in the St. Jude LIFE and CCSS cohorts. These two studies represent the largest survivor cohorts in North America and are unique in their comprehensive collection of data, including detailed treatment exposures, long-term health outcomes, genetic information, and lifestyle factors.
"We found the burden of second cancer in survivors of childhood cancer is largely contributed by pediatric treatment exposures and genetic predisposition," stated Dr. Sapkota. "We’ve known treatment exposures and genetics were associated with second cancer risk, but this is the first time we’ve been able to attribute the proportion of their contributions to that risk at the population level."
Previous research had often examined these risk factors in isolation, making it difficult to ascertain their relative importance in a real-world population. By integrating such a vast and detailed dataset, the St. Jude scientists were able to conduct a sophisticated, population-level attribution analysis, comparing the contributions of various factors to the occurrence of secondary cancers.
Co-author Greg Armstrong, MD, MSCE, chair of the St. Jude Department of Epidemiology and Cancer Control, underscored the unique capabilities of these combined cohorts: "This kind of high-impact discovery is only possible in the CCSS and SJLIFE cohorts, that in combination, have more than 12,000 survivors with genetic sequencing." This unparalleled resource allowed for an unprecedented level of granularity in dissecting the complex etiology of secondary malignancies.
Dissecting the Risk Factors: A Proportional Analysis
The study meticulously quantified the proportional contributions of different factors to the overall risk of secondary cancers, offering clear insights into their relative importance.
Radiation: The Foremost Culprit, Yet Progress Continues
Consistent with established knowledge, radiation exposure emerged as the most significant contributor to secondary cancer risk, accounting for approximately 40% or more of the total risk. Radiation, while highly effective in eradicating primary tumors, is a known carcinogen, and its long-term adverse effects have been extensively documented. This finding reinforces the critical efforts already underway in modern pediatric oncology. Over the past few decades, therapeutic protocols have undergone significant evolution, with a concerted focus on reducing radiation doses, utilizing more precise delivery methods, and, where possible, replacing radiation with other effective treatments to minimize late effects. The study’s data further validates these ongoing strategic shifts in clinical practice.
Chemotherapy: A Variable but Significant Impact
The contribution of chemotherapy to secondary cancer risk was found to be more varied, ranging from 8% to 35%, depending on the specific type of subsequent cancer. Chemotherapeutic agents are a diverse group of drugs, each with distinct mechanisms of action and different side-effect profiles. While their immediate role in curing primary cancers is undeniable, many chemotherapies can damage DNA, suppress the immune system, or induce chronic inflammation, all of which can increase the risk of developing a second cancer years later. The study’s ability to quantify this variable contribution highlights the need for continued research into the specific long-term effects of different chemotherapy regimens.
The Surprising Power of Genetics: Challenging Conventional Wisdom
Perhaps the most revelatory finding of the study pertained to the substantial and often underestimated role of genetic predisposition. The researchers delved into the genetic landscape of the survivors, examining hundreds of common genetic variants previously associated with cancer risk in the general population, which are collectively summarized as a "polygenic risk score" (PRS). They also considered some rare genetic variants.
The polygenic risk score approach revealed that, depending on the specific type of secondary cancer, genetic predisposition contributed between 5% and 37% of the total risk. This finding directly challenges long-held assumptions within the field.
"Our findings showed that genetics can be equally or more important than chemotherapy in some second cancers, which is counter to conventional wisdom in the field," Dr. Sapkota emphasized. This paradigm shift suggests that while treatment exposures have historically been the primary focus, a patient’s inherent genetic vulnerabilities play a far more critical role than previously appreciated.
Yutaka Yasui, PhD, a co-author from the St. Jude Department of Epidemiology and Cancer Control, commented on the practical implications of this genetic insight: "Polygenic risk scores are developed for all kinds of diseases for personalized medicine, but generally with precision below what is required for clinical utility in the general population. Among survivors of childhood cancer and for estimating their risk of certain types of subsequent cancer, however, they may provide useful information in conjunction with therapy exposures." This suggests that while PRS might not be universally applicable for broad population screening, their utility becomes significantly enhanced within the specific context of childhood cancer survivors, especially when integrated with their detailed treatment histories.
Lifestyle: A Long-Term Investment, Potentially Underestimated in Younger Cohorts
In contrast to the significant contributions of treatment and genetics, lifestyle factors such as diet and exercise appeared to play a comparatively smaller role in secondary cancer risk within this study, accounting for only 1% to 6%. This finding, however, comes with a crucial caveat. The survivors included in this analysis were primarily in their 20s and 30s. At this relatively young age, the cumulative effects of lifestyle choices on cancer development may not yet have fully manifested.
Dr. Sapkota cautioned against misinterpreting this particular finding: "We know healthy lifestyle choices are important for survivors. In this study, we focused only on the risk of second cancers, which may not be strongly impacted by lifestyle at this young age. However, other research has shown the benefits of healthy choices on other late effects, such as protecting cardiac wellbeing, so it is still important for clinicians to encourage — and patients to seek — a healthy lifestyle." This underscores that while lifestyle’s impact on secondary cancer risk might take longer to become apparent, its overall benefits for the holistic health and wellbeing of survivors remain undeniable and crucial.
Reshaping Clinical Practice and Survivor Care: A New Era of Personalization
The implications of this study are profound, signaling a transformative shift in how physicians assess and manage the long-term health of childhood cancer survivors.
Personalized Screening and Surveillance: Tailoring Care to Individual Risk
The most immediate impact of these findings will be on the development of more personalized screening and surveillance protocols. "Historically, we have paid attention to survivors’ treatment exposures when determining second cancer risk," Dr. Sapkota noted. "Our study suggests that we need to better account for genetic predisposition in this population."
This means that clinicians will increasingly need to integrate a patient’s genetic profile alongside their detailed treatment history when evaluating their risk for secondary cancers. Survivors identified with a strong genetic predisposition, combined with high-risk treatment exposures, could benefit from more frequent, intensive, or targeted cancer screenings. This proactive approach could lead to earlier detection of secondary malignancies, when they are typically more responsive to treatment, significantly improving survival outcomes.
Empowering Survivors: Informed Advocacy and Shared Decision-Making
Beyond clinical protocols, this research empowers survivors themselves. Armed with a clearer understanding of their unique combination of treatment-related, genetic, and lifestyle risk factors, individuals can become more informed advocates for their own health. This knowledge facilitates more productive conversations with healthcare providers, enabling survivors to actively participate in shared decision-making regarding their surveillance strategies and lifestyle choices. Knowing their specific genetic vulnerabilities could motivate some survivors to adhere more diligently to screening recommendations or adopt healthier habits.
Future Research Directions: Unlocking Deeper Insights
This study also opens numerous avenues for future research. Scientists will likely focus on refining polygenic risk scores to enhance their predictive power for specific secondary cancer types. Further investigation into gene-environment interactions – how genetic predispositions might modify the impact of treatment exposures or lifestyle choices – will be crucial. Understanding the underlying biological mechanisms by which certain genetic variants increase susceptibility to secondary cancers following specific treatments could also lead to novel preventive or therapeutic interventions. The long-term follow-up of these large cohorts will also be essential to fully understand the evolving role of lifestyle factors as survivors age.
Policy and Funding Implications: Sustaining Long-Term Studies
The success of this study highlights the immense value of sustained investment in long-term cohort studies like St. Jude LIFE and CCSS. These unique resources, built over decades, are indispensable for understanding the protracted and complex health trajectories of childhood cancer survivors. Continued funding and policy support will be critical to ensure these studies can continue to generate the vital data needed to improve survivor care globally.
A Renewed Focus on Prevention and Early Detection
Ultimately, the goal of this research is to extend and improve the lives of childhood cancer survivors. "Second cancers remain the leading cause of mortality for childhood cancer survivors," Dr. Sapkota reiterated. "Now that we have quantified the contributions of treatment, genetics and lifestyle to the risk of secondary disease, we have a better understanding of where to focus efforts to prevent, detect and treat these cancers, and hopefully extend these survivors’ lives."
By providing a clearer, more nuanced understanding of secondary cancer risk, the St. Jude study marks a pivotal moment in survivor care. It moves the field closer to a future where every childhood cancer survivor receives truly personalized care, tailored to their individual risk profile, allowing them to live longer, healthier lives free from the specter of subsequent malignancies.
Authors and Funding
The study’s first author is Achal Neupane, of St. Jude. The study’s other authors are Siddhant Taneja, Jennifer French, Matthew Ehrhardt, Tara Brinkman, Rachel Webster, Jun Yang, Kirsten Ness, Melissa Hudson, Gregory Armstrong, Leslie Robison and Yutaka Yasui; St. Jude; Qi Liu; University of Alberta; Cindy Im, Lucie Turcotte and Joseph Neglia; University of Minnesota; Monica Gramatges, Baylor College of Medicine; Rebecca Howell, University of Texas MD Anderson Cancer Center and Smita Bhatia; University of Alabama at Birmingham.
The study was supported by grants from the National Cancer Institute (R01HL173881, R01CA216354, R21CA261833, U24CA55727, U01CA195547 and CA21765) and ALSAC, the fundraising and awareness organization of St. Jude.
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