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Cross-border U.S.-Mexican collaboration drives up ALL survival



Survival from pediatric acute lymphoblastic leukemia (ALL) in a Mexican hospital improved significantly through a close cross-border collaboration with a nearby U.S. center that provided training and improved access.

A team from a hospital in San Diego combined a previously established training program from the World Health Organization with a new collaboration, which resulted in improvements in care standards and sustainability of care in a center in Tijuana, Mexico, just 23 miles away.

Implementation of the program in 2013 led to a significant 6% improvement in 5-year overall survival for children with ALL.

For patients at standard risk, 5-year overall survival increased from 73% to 100% after implementation of the program.

“This is really remarkable because this survival is the same as we have here in San Diego,” commented Paula Aristizabal, MD, MAS, a pediatric hematologist/oncologist at Rady Children’s Hospital, San Diego, at a press briefing before the annual meeting of the American Society of Clinical Oncology.

The findings show that “sustained improvements in cancer outcomes in low- and middle-income countries [LMICs] are feasible with innovative cross-border programs, particularly in borders that are shared” between a high- and low-income country, she commented. In other words, “it takes a village in both countries” to drive up standards.

Dr. Aristizabal also noted that the partnership will continue with a particularly focus on improving survival among patients with high-risk disease.

“We like to call it ‘twinning,’ because that means we are twins forever,” she said. “This is not a marriage that can be dissolved.”

‘Huge survival gap’

“The burden of childhood cancer has increased globally, but unfortunately, survival in low- and middle-income countries has not improved at the same level as in high-income countries,” Dr. Aristizabal commented.

This has resulted in a “huge survival gap” between high-income countries and the LMICs. ALL is now a leading cause of death among children in these countries, she commented.

“This study illustrates collaborative strategies that can be put into place today that could greatly improve outcomes for children with cancer globally,” commented Julie R. Gralow, MD, ASCO chief medical officer and executive vice president.

Speaking at the press conference, she added: “As I’ve heard Princess Dina Mired of Jordan say many times: ‘Your ZIP code should not determine if you survive cancer.’ ”

She said the differences in ALL survival between the United States and Mexico are an “example of children being so close in terms of proximity not having the same advantages.”

Also commenting, ASCO President Eric Winer, MD, from the Yale Cancer Center, New Haven, Conn., asked whether the proximity of the hospitals in San Diego and Tijuana “makes a difference, or do you think this is something that done ... at a distance?”

Dr. Aristizabal said that the proximity between the institutions “has been extremely helpful,” as they can go between hospitals in just 30 minutes.

However, “one of the things that we learned with COVID is that we can do a lot of things remotely,” she answered.

“Some of the projects that we started in Tijuana, through our collaboration with St. Jude Children’s Research Hospital, we have been able to implement in many other centers in Mexico,” she said.

Study details

Rady Children’s Hospital partnered with the public sector in Baja California, with the aim of improving outcomes in children’s cancer, she explained.

In 2008, the team collaborated with St. Jude Children’s Research Hospital, Memphis, to establish a training program in the Hospital General Tijuana in Tijuana that shared knowledge, technology, and organizational skills.

The team also consulted on clinical cases and set up education and research programs, all with the aim of building capacity and sustainability in Mexico.

“As the number of leukemia patients increased, we wanted to decrease depending on their international collaborators in the U.S. and ensure long-term sustainability,” Dr. Aristizabal explained.

This led in 2013 to the implementation of the WHO Framework for Action HSS training model, which has several components, including health service delivery.

Combined with the previously established model, the overall goals of the program were to improve health outcomes, systems efficiency, timely access to care, and social and financial risk protection.

Dr. Aristizabal said in an interview that this involved developing highly specific leukemia treatment guidelines, which have now gone through three iterations, as well as guidelines for supportive care.

Working with a local foundation, the team has also “focused on providing psychosocial support, nutritional support, a shelter for families that live 12-14 hours away from the pediatric cancer center, as well as food subsidies, trying to address financial toxicity and food insecurity in these families.”

Impact of the collaboration

To assess the impact of the WHO framework, the researchers conducted a study that involved 109 children with ALL who were treated at Hospital General Tijuana over the preimplementation phase in 2008-2012 and the postimplementation phase in 2013-2017.

The mean age of the patients was 7.04 years, and 50.4% were girls. The majority (67%) were classified as having high-risk disease.

Over the entire study period, the 5-year overall survival rate was 65%. Analysis revealed that between the pre- and postimplementation periods, 5-year overall survival increased from 59% to 65%, which Dr. Aristizabal described as “a significant improvement.”

Among high-risk patients, the improvement in 5-year survival between the pre- and postimplementation period went from 48% to 55%.

“This is an area for improvement,” Dr. Aristizabal said, “and we’re working on additional strategies to help improve survival for high-risk patients.

The study was funded by Rady Children’s Hospital, the Mexican Secretary of Health, and the Patronato Foundation. Dr. Aristizabal and coauthors reported no relevant financial relationships. Dr. Gralow reported relationships with Genentech and Roche. Dr. Winer reported relationships with Leap Therapeutics, Jounce Therapeutics, Carrick Therapeutics, and Genentech.

A version of this article first appeared on

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