Top Line: Is MRI an effective tool in identifying low risk, early stage breast cancer?
The Study: PROSPECT was a prospective, two-arm, non-randomized study from Australia with the hypothesis that lesions detected by MRI may be the source of breast cancer recurrences that radiation helps prevent. Thus, it was designed to use MRI to identify a low-risk subset of patients who may forego adjuvant radiation without increasing recurrence risk. It included 443 women ≥50 years old with cT1N0 non-TNBC. 36% were under 60 years old, 9% had grade 3 tumors, 12% had lobular carcinoma, 96% had hormone receptor positive/HER2 negative disease, and 61% had DCIS. They all had MRI, and 75% were confirmed to have unifocal T1 tumors eligible to continue on to breast conservation surgery. MRI identified additional mammographically occult invasive tumors in 11% of patients. Of those with unifocal disease on MRI, 65% (45% of the original cohort) had unifocal, pT1N0-N1mi disease without LVI or extensive DCIS on final pathology, and they received indicated adjuvant systemic therapy without adjuvant radiation. The rest received standard adjuvant treatment including radiation. Among 201 patients who had surgery without radiation, the rate of ipsilateral invasive recurrence was just 1% at 5 years. Obviously, longer follow up is necessary in low risk populations, but this study suggests MRI is a useful tool in identifying patients with low risk of recurrence without adjuvant radiation.
TBL: In the PROSPECT study, preoperative MRI identified a subset of early stage breast cancer patients at low risk of recurrence after breast conservation surgery without adjuvant radiation. | Mann, Lancet 2023
The Study: PROSPECT was a prospective, two-arm, non-randomized study from Australia with the hypothesis that lesions detected by MRI may be the source of breast cancer recurrences that radiation helps prevent. Thus, it was designed to use MRI to identify a low-risk subset of patients who may forego adjuvant radiation without increasing recurrence risk. It included 443 women ≥50 years old with cT1N0 non-TNBC. 36% were under 60 years old, 9% had grade 3 tumors, 12% had lobular carcinoma, 96% had hormone receptor positive/HER2 negative disease, and 61% had DCIS. They all had MRI, and 75% were confirmed to have unifocal T1 tumors eligible to continue on to breast conservation surgery. MRI identified additional mammographically occult invasive tumors in 11% of patients. Of those with unifocal disease on MRI, 65% (45% of the original cohort) had unifocal, pT1N0-N1mi disease without LVI or extensive DCIS on final pathology, and they received indicated adjuvant systemic therapy without adjuvant radiation. The rest received standard adjuvant treatment including radiation. Among 201 patients who had surgery without radiation, the rate of ipsilateral invasive recurrence was just 1% at 5 years. Obviously, longer follow up is necessary in low risk populations, but this study suggests MRI is a useful tool in identifying patients with low risk of recurrence without adjuvant radiation.
TBL: In the PROSPECT study, preoperative MRI identified a subset of early stage breast cancer patients at low risk of recurrence after breast conservation surgery without adjuvant radiation. | Mann, Lancet 2023