75 Comparing 21-Gene Assay Recurrence Scores Before and After Preoperative Radiation Boost in Patients Enrolled in a Phase 2 Prospective Clinical Trial

Publication
Article
Miami Breast Cancer Conference® Abstracts Supplement42nd Annual Miami Breast Cancer Conference® - Abstracts
Volume 39
Issue 4
Pages: 66

75 Comparing 21-Gene Assay Recurrence Scores Before and After Preoperative Radiation Boost in Patients Enrolled in a Phase 2 Prospective Clinical Trial

75 Comparing 21-Gene Assay Recurrence Scores Before and After Preoperative Radiation Boost in Patients Enrolled in a Phase 2 Prospective Clinical Trial

Background/Significance

Early-stage breast cancer is commonly treated with breast-conserving surgery (BCS) followed by whole breast irradiation (WBI). A radiation boost to the tumor bed is also recommended in some cases, is dependent on patient age and disease characteristics, and is usually delivered following BCS and WBI. We conducted a prospective, phase 2 clinical trial (NCT04871516) in which the radiation boost was delivered preoperatively instead of postoperatively, the first results of which have been previously published. Due to concerns that the preoperative radiation boost could possibly alter the genomic profile of the tumor, we compared the 21-gene assay results (Oncotype DX Breast Recurrence Score) before and after the boost, to see if a change may have altered systemic therapy.

Materials and Methods

Patients received a preoperative boost of 13.32 Gy in 4 daily fractions, followed by BCS 1 to 3 weeks after, followed by WBI of 36.63 Gy in 11 daily fractions 3 to 8 weeks after surgery. A total of 55 patients were enrolled in the trial. We randomly selected 17 patients to compare the 21-gene assay results before and after the boost. We used paired Student’s t-test to see whether the difference between the 2 sets of scores is statistically significant.

Results

Tissue was sufficient to run the assay on the core needle biopsy and the lumpectomy specimens in 15 patients. All patients had clinically negative axillary nodes. The median age at diagnosis was 68 years (range, 53-79). Average tumor size was 13.15 mm (range, 7-21). There were 3 lobular, 1 mucinous, and 11 ductal invasive carcinomas. All tumors were hormone receptor–positive and HER2-negative. The mean 21-gene assay result prior to the radiation boost was 12 (± SD, 7.92), and after was 13.47 (± SD 6.93). Paired Student’s t-test showed no significant difference between the pre- and postradiation results (t = 0.5399, P = .6). In 9 of 15 (60%) patients, the results of the 21-gene assay slightly increased after the boost by an average of 4.78 points (± SD, 2.05), and in 6 of 15 (40%), they slightly decreased by an average of 3.5 points (± SD, 2.74). In none of these 15 patients would the preoperative boost have altered systemic therapy.

Conclusion

In this cohort of patients from our preoperative radiation boost trial, results of the 21-gene assay were not significantly changed after the radiation boost. This indicates that, in this protocol, preoperative radiation boost would likely not alter systemic therapy decisions.

Articles in this issue

56 Paternal vs Maternal Inheritance of a BRCA Mutation: Is There a Difference in Presentation and Stage of Breast Cancer at Diagnosis?
56 Paternal vs Maternal Inheritance of a BRCA Mutation: Is There a Difference in Presentation and Stage of Breast Cancer at Diagnosis?
57 Tumor Morphology Concordance in Multifocal/Multicentric Triple- Negative and HER2+ Breast Cancers
57 Tumor Morphology Concordance in Multifocal/Multicentric Triple- Negative and HER2+ Breast Cancers
59 Are Choosing Wisely Guidelines Applicable to Patients With a High Ki-67 Proliferation Index and Magee Equation Score?
59 Are Choosing Wisely Guidelines Applicable to Patients With a High Ki-67 Proliferation Index and Magee Equation Score?
60 Nipple-Sparing Mastectomy in Patients With BRCA and Other Breast Cancer–Related Gene Mutations
60 Nipple-Sparing Mastectomy in Patients With BRCA and Other Breast Cancer–Related Gene Mutations
61 Can the Use of Tumor Margin Markers for Intraoperative Specimen Radiographs Decrease the Rate of Margin Positivity During Breast Conservation Therapy?
61 Can the Use of Tumor Margin Markers for Intraoperative Specimen Radiographs Decrease the Rate of Margin Positivity During Breast Conservation Therapy?
63 Intraoperative Radiation and External Beam Radiation After Breast-Conserving Surgery in an Ethnic Minority Population: Patient Reported Outcomes Using BREAST-Q
63 Intraoperative Radiation and External Beam Radiation After Breast-Conserving Surgery in an Ethnic Minority Population: Patient Reported Outcomes Using BREAST-Q
64 A Prospective Study to Accurately Define the Nipple-Ward Margins in Patients Undergoing Lumpectomy for Breast Cancer
64 A Prospective Study to Accurately Define the Nipple-Ward Margins in Patients Undergoing Lumpectomy for Breast Cancer
65 The Outcomes of Nipple Sparing Goldilocks Mastectomy in a Primarily Overweight and Obese Population
65 The Outcomes of Nipple Sparing Goldilocks Mastectomy in a Primarily Overweight and Obese Population
67 Confocal Laser Scanning Microscopy (CLSM) for Intraoperative Histopathological Margin Assessment in Breast Conservation Surgery
67 Confocal Laser Scanning Microscopy (CLSM) for Intraoperative Histopathological Margin Assessment in Breast Conservation Surgery
68 Upper Extremity Disability Assessment Following Breast Cancer Surgery Using QuickDASH in an Ethnic Minority Population
68 Upper Extremity Disability Assessment Following Breast Cancer Surgery Using QuickDASH in an Ethnic Minority Population
70 Malignancy Upgrade Rates of Discordant Breast Lesions
70 Malignancy Upgrade Rates of Discordant Breast Lesions
71 Beyond the Surface: Suspicious Nipple Lesions
71 Beyond the Surface: Suspicious Nipple Lesions
72 Breast Cancer After Breast Augmentation: A Multicenter Collaborative Study Of Patient Management and Outcomes
72 Breast Cancer After Breast Augmentation: A Multicenter Collaborative Study Of Patient Management and Outcomes
73 Short- and Long-Term Outcomes in Use of Titanium-Coated Polypropylene Meshes in Immediate Breast Reconstruction: A Cost-Effective and Safe Option?
73 Short- and Long-Term Outcomes in Use of Titanium-Coated Polypropylene Meshes in Immediate Breast Reconstruction: A Cost-Effective and Safe Option?
74 Lessons Learned From a Breast Surgery ERAS Program in an Oncologic Ambulatory Center
74 Lessons Learned From a Breast Surgery ERAS Program in an Oncologic Ambulatory Center

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