Treatment modifications in the pre-surgery setting led to a lower rate of pathologic complete response in Black patients with breast cancer, the researchers found.
Pre-surgical treatment interruptions can negatively impact early-stage breast cancer outcomes, and a recent study presented at the 2021 San Antonio Breast Cancer Symposium (SABCS) found that Black patients experience these therapy changes more often than their White counterparts.
“While common, treatment modification or discontinuation has the potential to impair responses,” the researchers wrote in their poster presentation. “We found that African American patients were more likely to have treatment modifications in this cohort, which may contribute to poorer outcomes in this patient population.”
Researchers conducted a retrospective review of 173 patients who had received neoadjuvant (pre-surgical) therapy from January 2010 through March 2020 and separated the patients into two cohorts: a group of 114 patients who received a scheduled regimen (SR); and another group of 59 patients who received a modified regimen (MR).
Although there were nearly double the number of patients in the SR group than in the MR group, Black patients accounted for 59% of the MR cohort.
In the MR group, a significantly lower proportion of patients achieved a pathologic complete response — meaning that there were no detectable signs of cancer — compared with the SR group. Moreover, similar to previous study findings, 42% of Black patients had treatment interruptions compared with 25% of White patients.
“During neoadjuvant therapy in breast cancer, treatment interruptions may impact rates of pathologic complete response and ultimately increase risk of recurrence,” the study authors wrote in their poster.
Six patients (10%) had early discontinuation of doxorubicin and cyclophosphamide; 25 patients (42%) had an early discontinuation of a taxane therapy; seven patients (12%) had an anti-HER2 therapy discontinued; and 21 patients (36%) had dose reductions throughout their therapy.
The study authors observed a pathologic complete response rate of 42% in the SR group, compared with less than half that (20%) in the MR group.
The researchers also used a modeling platform called TumorScope to analyze patient data in the MR group and simulate what their responses to treatment may have been if patients had received the full, uninterrupted dose of their treatment.
The simulation demonstrated that without treatment interruption, 10 additional patients (5.6%) in that group would have been able to achieve a pathologic complete response. In the simulation, 100% of patients receiving SR had a complete response in comparison with 81.7% of those who would experience treatment interruptions.
TumorScope was previously evaluated in a separate study to determine its effectiveness and was used in several other studies and analyses presented at this year’s SABCS. According to the researchers of this study, the results show that TumorScope can be used to estimate the impact of variable dosing before clinicians decide to interrupt a patient’s treatment.
Furthermore, researchers believe that TumorScope can evaluate individual treatments being considered for this patient population to support de-escalation of therapy ahead of time but note that further study is needed.
“In this proof-of-concept study, (TumorScope) can be used to estimate the impact of variable dosing on (pathological complete response; allowing clinicians and patients to make better informed decisions on the impact of regimen modifications on response to (neoadjuvant treatment),” the researchers wrote.
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