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Chloe Williams

Supervisor(s): Michael Zappitelli
Award:  KRESCENT Summer Studentship
Institution:  The Hospital for Sick Children
Year: 2024

Project Title: KIdney aNd blooD prESsure ouTcomes in Childhood Cancer Survivors  

Chloe Williams is an undergraduate research student at The Hospital for Sick Children (Sick Kids) under the supervision of Dr. Michael Zappitelli. She will be entering her third year of the Honours Life Sciences program at McMaster University this fall. Her research journey began at age 17 when she was selected and placed in the Zappitelli Lab through the Sick Kids Student Advancement Research (StAR) program. She has since returned for her third summer in the lab. Her work focuses on hypertension (HTN) and chronic kidney disease (CKD) in children. When Chloe is away from the lab she enjoys competitive dance. She represented Team Canada in the 2023 Dance World Cup in Portugal and competes on the McMaster Varsity Dance Team.
Lay Summary
Background: Due to better cancer research and treatments, more children with cancer are surviving, and for longer. However, childhood cancer survivors (CCS) are at high risk for many complications later in life. During cancer treatment, many children receive therapies and have procedures that are toxic to the kidneys.  Many of these necessary treatments can cause episodes of sudden kidney tissue damage, known as acute kidney injury (AKI). Because these children receive many types of treatments repeatedly, they can have multiple AKIs which can add up to cause long-term kidney damage.  Long-term, permanent kidney damage can cause chronic kidney disease (CKD) and may also cause hypertension. Both CKD and hypertension are well-known to put people at higher risk for having heart disease, placing them at higher risk for death. Hypertension is treatable with lifestyle changes and medications.  Hypertension is really important to treat because it can worsen kidney disease and cause heart disease and death in the long term.  In Ontario, providers follow the Children’s Oncology Group (COG) guidelines to monitor children after the end of their cancer treatments. However, the COG guidelines do not follow childrens’ blood pressure (BP) guidelines (American Academy of Pediatrics) very well.  
Purpose: Using data from children treated for cancer at the largest pediatric cancer centre in Ontario, we aim to determine 1) how frequently CCS are being evaluated for hypertension after cancer treatment, 2) whether CCS with hypertension are being checked and tested for complications of hypertension, 3) How often hypertension occurs in the first 5 years after the end of cancer treatment, and 4) whether there are certain patient or cancer treatment factors that affect whether CCS get evaluated for hypertension.  Understanding what doctors are currently doing to follow BP health will help us to understand where we need to improve healthcare to increase screening and treatment for hypertension.  
Methods: In this retrospective study, we will look back in time at the medical records (e.g., cancer diagnosis/treatment data) and laboratory data (e.g., kidney function tests; BPs; heart ultrasounds) of approximately 2000 children who were diagnosed with and treated for cancer at SickKids Hospital (Toronto) between 2016–2020. We will compare CCS who undergo screening for hypertension with those who do not, and those who receive appropriate complications monitoring with those who do not.

Anticipated Outcomes: We expect that CCS are receiving less frequent assessments and monitoring for their BP function than recommended. Additionally, we anticipate that hypertension is very common in CCS. 
Patient Engagement: Throughout our study we have included two patient partners who have been key contributors to its development. They have provided invaluable feedback on various aspects of the study design and data collection materials. We plan to invite them to be co-authors on the final manuscript and to review the study. 

Relevance to Patients and Community: Approximately 30,000 Canadians are currently CCS. Most large studies examining the effects of cancer treatment on kidney health in CCS focus on adults who have survived more than 10 years post-cancer treatment end. However, the onset and burden of hypertension in the first 5 years post-cancer treatment end remains unknown, highlighting a crucial period for screening, detection, and prevention efforts. Hypertension is a significant and treatable cardiovascular risk factor, and early intervention can modify their disease trajectory. This data will help develop targeted implementation goals aimed at improving kidney health care processes, enhancing outcomes for CCS, and advancing the standard of evidence-based care for children treated for cancer.  

Conclusion: Shedding light on patterns of current hypertension screening and complication monitoring practices, and early post-cancer treatment disease incidence, can help us identify the burden of hypertension, and gaps in existing long-term follow-up practices for CCS. We hope that this work will address national and international priorities to improve health in CCS, plan trials to mitigate the development of hypertension, and improve long-term health in CCS.