Breast Cancer, Early-Stage Breast Carcinoma, Hormone Receptor-Positive Breast Cancer, HER2-Negative Breast Cancer
Conditions
Keywords
SOLIS, single-fraction SDRT, stereotactic radiosurgery, lumpectomy omission, non-operative, HR-positive, HER2-negative
Brief summary
SOLIS is a prospective, single-arm, single-institution pilot trial evaluating single-fraction stereotactic radiotherapy (24 Gy to the planning target volume with a simultaneous integrated boost of 30 Gy to the clinical target volume) delivered with a cleared linear accelerator as definitive non-operative local treatment for early-stage, hormone receptor-positive, HER2-negative breast cancer with planned omission of lumpectomy. Adjuvant endocrine therapy is prescribed on-label. The primary endpoint is the incidence of CTCAE v5.0 Grade ≥2 skin adverse events within 90 days of treatment, monitored with a pre-specified Bayesian safety stopping rule. Secondary endpoints include biopsy-confirmed absence of residual invasive carcinoma at 12 months, imaging response on multiparametric MRI and FDG PET/CT, late toxicity, cosmesis, patient-reported outcomes, salvage surgery, and disease control through 36 months.
Interventions
RADIATIONStereotactic Radiation Therapy
Single fraction 24 Gy to PTV with SIB 30 Gy to CTV on Varian Edge with image guidance.
DRUGEndocrine Therapy
Adjuvant aromatase inhibitor or tamoxifen initiated within 30 days of SDRT; on-label; recommended 5 years.
Sponsors
Renaissance Institute of Precision Oncology and Radiosurgery
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
50 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Invasive ductal carcinoma or favorable special histology confirmed by core biopsy. * Unifocal tumor ≤2 cm; estrogen receptor-positive and HER2-negative; grade 1-2; clinically node-negative (cN0). * Age ≥65, or age 50-64 when surgery is unsuitable or declined (capped at 10 of 30 participants). * Tumor ≥5 mm from skin and pectoralis; willing to receive adjuvant endocrine therapy. * Zubrod performance status 0-2; able to undergo MRI and FDG PET/CT; informed consent.
Exclusion criteria
* Multifocal or multicentric disease; pure DCIS; invasive lobular carcinoma \>10%; extensive intraductal component or diffuse calcifications. * Grade 3, triple-negative, or HER2-positive disease; nodal or distant metastases. * Prior ipsilateral breast radiation or excisional biopsy/lumpectomy; neoadjuvant chemotherapy. * Tumor \<5 mm from skin or pectoralis; inability to meet dose constraints or PTV \>60 cm³. * Connective tissue disease; prohibited other malignancy; pregnancy or lactation. * Pathogenic BRCA1, BRCA2, PALB2, or TP53 variant; investigator judgment that participation is inappropriate.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Incidence of CTCAE v5.0 Grade ≥2 skin adverse events | 90 days after SDRT | Proportion of treated patients with at least one Grade ≥2 skin AE within 90 days, graded per protocol by study research nurse practitioner. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Absence of residual invasive carcinoma on protocol-mandated tissue sampling | 12 months | Proportion with no residual invasive carcinoma on mandated sampling. |
| Modified RECIST 1.1 response on multiparametric breast MRI | Up to 36 months | MRI response by modified RECIST 1.1. |
| PERCIST 1.0 metabolic response on FDG PET/CT | 6 and 12 months | Metabolic response assessed by PERCIST 1.0. |
| Late Grade ≥2 skin adverse events | From 90 days through 36 months | Incidence of late Grade ≥2 skin adverse events after treatment. |
| Rate of salvage surgery | Through 36 months | Proportion of participants undergoing salvage surgery. |
| Ipsilateral breast tumor recurrence | 12, 24, and 36 months | Incidence of ipsilateral breast tumor recurrence. |
| BREAST-Q Breast Conserving Therapy module scores | Baseline through 36 months | Change in BREAST-Q Breast Conserving Therapy module scores. |
Countries
United States
Contacts
CONTACTJulia Pierson
Outcome results
None listed