UC radiation oncology experts present at national conference

In standard radiation treatment, entire tumors receive the same dose of radiation. Cancer Center researchers including Andrew Frankart, MD, are testing the application of a different method called lattice therapy, and he will present three posters detailing research into lattice therapy at ASTRO. 

“In comparison to a standard radiation plan, lattice therapy delivers higher doses to parts of a tumor and lower doses to other parts,” said Frankart, MD, a Cancer Center physician-researcher and assistant professor of radiation oncology in UC’s College of Medicine. “This has the potential to both improve anti-tumor effects and lead to safer delivery of radiation, especially for large tumors that currently do not respond well to treatment.” 

Lattice therapy is a relatively new form of radiation therapy, and there is not currently a standard approach to plan and deliver the therapy to patients.  

“These projects evaluated our ability to generate these complex plans in a timeframe that is feasible for clinical use and to effectively apply these plans to tumors in various challenging sites in the body,” Frankart said. 

The studies used an automated planning approach created by Cancer Center medical physicist Nitin Kumar, MS, via computer-based modeling of representative tumors in the UC Department of Radiation Oncology’s treatment planning system. The team found they were able to generate lattice plans in an average of 20 minutes. Traditional radiation plans take several hours to put together. 

“Essentially, our planning approach takes a tumor of a given shape and size and automatically develops a plan to distribute high- and low-dose regions according to criteria we set for each tumor,” Frankart said. “These plans were feasible to deliver in large head and neck and liver tumors, accomplishing our dual aims of increasing dose within tumors while minimizing exposure of normal tissues.” 

The team now plans to test lattice therapy in a clinical trial for patients with large tumors that are currently not as responsive to treatment, with the hope to apply the technique more broadly in the future. 

Patients with oral cavity cancers (including tongue cancers) typically are treated with surgery followed by radiation and sometimes chemotherapy. But how does the total length of time from the start to the end of treatments, known as treatment package time (TPT), affect patient outcomes?

That was the question UC College of Medicine student Taylor Petery asked in a recent study. Looking at a large patient cohort treated at the Cancer Center, Petery found it is ideal for oral cavity cancer patients to complete all of their treatments in 105 days or less. A TPT longer than that was significantly associated with worse overall survival and recurrence rates. 

Petery also found that delays including the cancer being at a more advanced stage and patients’ smoking status independently led to worse survival outcomes. In the cohort, 56% of patients required hospitalization between surgery and radiation, and 76% were prior or current smokers at the time of diagnosis.

“Future studies and analysis would hope to identify and characterize factors contributing to treatment delay and minimizing TPT,” Petery said. “Smoking history should be further explored for its potential contribution to treatment delay, as should the causes of prolonged postoperative hospitalization and unexpected readmissions.”

After initial treatment, high-grade gliomas (HGG), a type of fast-spreading brain tumor, often recur and require additional treatment, but there is currently no standard of care for how to do so.

Cancer Center researchers including Taylor MacDonald, DO, looked at the neurologic effects of a second round of radiation delivered by traditional photon reirradiation compared to proton reirradiation. Proton therapy uses a more precise proton beam to target tumors with radiation that aims to reduce damage to surrounding healthy tissue. 

The researchers found high grade neurologic toxicity appeared to occur more often and earlier with proton treatment, but survival was similar and slightly better with protons. It is unclear whether these are true findings or related to imbalances between the study arms, but the higher rate of neurologic events with proton reirradiation warrants further examination of the biologic impact of proton therapy and whether radiation doses are truly comparable between protons and photons.

The data additionally showed a correlation between proton reirradiation and increased pseudoprogression and radiation necrosis, according to MacDonald.

“Pseudoprogression is growth of a fast-growing tumor during radiation that continues to grow after radiation for a while before slowing down or stabilizing, but is ultimately not true tumor progression,” said MacDonald, a Radiation Oncology resident at the Cancer Center. “Radiation necrosis is similar but occurs due to swelling late (months or years) after radiation. Both can appear to be tumor growth or treatment failure but are expected and don’t necessarily reflect treatment failure or true tumor progression.

MacDonald said the team plans to further analyze proton therapy plans and compare them to the neurologic events patients experienced.