The role of radiotherapy in treating small early invasive breast cancer

Omission of Radiotherapy After Breast-Conserving Surgery for Women With Breast Cancer With Low Clinical and Genomic Risk: 5-Year Outcomes of IDEA

PURPOSE

Multiple studies have shown a low risk of ipsilateral breast events (IBEs) or other recurrences for selected patients age 65-70 years or older with stage I breast cancers treated with breast-conserving surgery (BCS) and endocrine therapy (ET) without adjuvant radiotherapy. We sought to evaluate whether younger postmenopausal patients could also be successfully treated without radiation therapy, adding a genomic assay to classic selection factors.

METHODS

Postmenopausal patients age 50-69 years with pT1N0 unifocal invasive breast cancer with margins ≥2 mm after BCS whose tumors were estrogen receptor-positive, progesterone receptor-positive, and human epidermal growth factor receptor 2-negative with Oncotype DX 21-gene recurrence score ≤18 were prospectively enrolled in a single-arm trial of radiotherapy omission if they consented to take at least 5 years of ET. The primary end point was the rate of locoregional recurrence 5 years after BCS.

RESULTS

Between June 2015 and October 2018, 200 eligible patients were enrolled. Among the 186 patients with clinical follow-up of at least 56 months, overall and breast cancer-specific survival rates at 5 years were both 100%. The 5-year freedom from any recurrence was 99% (95% CI, 96 to 100). Crude rates of IBEs for the entire follow-up period for patients age 50-59 years and age 60-69 years were 3.3% (2/60) and 3.6% (5/140), respectively; crude rates of overall recurrence were 5.0% (3/60) and 3.6% (5/140), respectively.

CONCLUSION

This trial achieved a very low risk of recurrence using a genomic assay in combination with classic clinical and biologic features for treatment selection, including postmenopausal patients younger than 60 years. Long-term follow-up of this trial and others will help determine whether the option of avoiding initial radiotherapy can be offered to a broader group of women than current guidelines recommend.

Margin status and survival outcomes after breast cancer conservation surgery: prospectively registered systematic review and meta-analysis

OBJECTIVE

To determine if margin involvement is associated with distant recurrence and to determine the required margin to minimise both local recurrence and distant recurrence in early stage invasive breast cancer.

DESIGN

Prospectively registered systematic review and meta-analysis of literature.

DATA SOURCES

Medline (PubMed), Embase, and Proquest online databases. Unpublished data were sought from study authors.

ELIGIBILITY CRITERIA

Eligible studies reported on patients undergoing breast conserving surgery (for stages I-III breast cancer), allowed an estimation of outcomes in relation to margin status, and followed up patients for a minimum of 60 months. Patients with ductal carcinoma in situ only or treated with neoadjuvant chemotherapy or by mastectomy were excluded. Where applicable, margins were categorised as tumour on ink (involved), close margins (no tumour on ink but <2 mm), and negative margins (≥2 mm).

RESULTS

68 studies from 1 January 1980 to 31 December 2021, comprising 112 140 patients with breast cancer, were included. Across all studies, 9.4% (95% confidence interval 6.8% to 12.8%) of patients had involved (tumour on ink) margins and 17.8% (13.0% to 23.9%) had tumour on ink or a close margin. The rate of distant recurrence was 25.4% (14.5% to 40.6%) in patients with tumour on ink, 8.4% (4.4% to 15.5%) in patients with tumour on ink or close, and 7.4% (3.9% to 13.6%) in patients with negative margins. Compared with negative margins, tumour on ink margins were associated with increased distant recurrence (hazard ratio 2.10, 95% confidence interval 1.65 to 2.69, P<0.001) and local recurrence (1.98, 1.66 to 2.36, P<0.001). Close margins were associated with increased distant recurrence (1.38, 1.13 to 1.69, P<0.001) and local recurrence (2.09, 1.39 to 3.13, P<0.001) compared with negative margins, after adjusting for receipt of adjuvant chemotherapy and radiotherapy. In five studies published since 2010, tumour on ink margins were associated with increased distant recurrence (2.41, 1.81 to 3.21, P<0.001) as were tumour on ink and close margins (1.44, 1.22 to 1.71, P<0.001) compared with negative margins.

CONCLUSIONS

Involved or close pathological margins after breast conserving surgery for early stage, invasive breast cancer are associated with increased distant recurrence and local recurrence. Surgeons should aim to achieve a minimum clear margin of at least 1 mm. On the basis of current evidence, international guidelines should be revised.

SYSTEMATIC REVIEW REGISTRATION

CRD42021232115.

The Diminishing Impact of Margin Definitions and Width on Local Recurrence Rates following Breast-Conserving Therapy for Early-Stage Invasive Cancer: A Meta-Analysis

BACKGROUND

The optimal tumor-free margin definition and width following breast-conserving therapy (BCT) for early-stage invasive cancers has been evaluated in previous meta-analyses and guidelines. We performed an updated meta-analysis to assess how improvements in treatment over time have affected the impact of margins on local recurrence (LR) rates over time.

METHODS

A systematic literature review identified 38 eligible studies comprising 54,502 patients treated between 1968 and 2010. Inclusion criteria included patients treated with BCT and minimum follow-up of 50 months, pathologic definitions of margin status explicitly stated, and LR data in relation to margin status. Data were pooled using a Bayesian logistic regression model to evaluate the risk of LR in relation to both margin status and study enrollment periods.

RESULTS

Median follow-up was 7.25 years. Absolute LR rates decreased over time for each margin width cohort, with maximum differences between negative margin groups of less than 1% for the most recent enrollment period. However, relative rates of LR between different margin groups remained stable over time.

CONCLUSIONS

With an additional 22,000 patients compared with the previous meta-analysis, this updated meta-analysis supports the consensus guideline of "no tumor on ink" for the majority of patients. Additionally, while concerns exist regarding a benefit with wider margins from previous studies, the analysis demonstrates the impact of margin width on LR rates has declined substantially over time, with very small differences between the narrowest and widest margin groups in the most recent cohort. Hence, older studies appear to have limited value to inform current management guidelines.

Efficacy of intraoperative entire-circumferential frozen section analysis of lumpectomy margins during breast-conserving surgery for breast cancer

BACKGROUND

Intraoperative frozen section analysis of the surgical margins during breast-conserving surgery (BCS) for breast cancer can reliably achieve clear surgical margins and prevent re-operations. The aim of this study was to assess intraoperative entire-circumferential frozen section analysis (IEFSA) of the lumpectomy margins during BCS.

METHODS

A total of 1029 patients who underwent BCS with IEFSA between June 2007 and July 2013 were available for assessment. The inner surfaces of the shaved lumpectomy margins were examined as frozen sections during BCS. The margins were defined as positive when the cancer cells were present within 5 mm from the edge of the outermost margins of the specimens.

RESULTS

Out of 1029 patients, 312 patients (30.3 %) had positive margins after the initial lumpectomy and underwent additional resections during BCS. Fourteen patients (1.4 %) underwent mastectomy following the results of additional resections during the first surgery. Of 1015 patients who completed BCS, 60 patients (5.9 %) were found to have positive margins in the final pathology. One patient (0.1 %) underwent re-operation after BCS while the residual diseases of the other 59 patients were judged to be minimal. Of the 312 patients who were judged to have positive margins after the initial lumpectomy with IEFSA, 53 patients (16.9 %) were found to have negative margins in the final pathology. At a median follow-up time of 54.1 months, one patient (0.1 %) had a recurrence of breast cancer in the preserved breast.

CONCLUSION

IEFSA is useful for preventing the need for re-operation and local recurrence after BCS.

The association of surgical margins and local recurrence in women with early-stage invasive breast cancer treated with breast-conserving therapy: a meta-analysis

PURPOSE

There is no consensus on what constitutes adequate negative margins in breast-conserving therapy (BCT). We systematically review the evidence on surgical margins in BCT for invasive breast cancer to support the development of clinical guidelines.

METHODS

Study-level meta-analysis of studies reporting local recurrence (LR) data relative to final microscopic margin status and the threshold distance for negative margins. LR proportion was modeled using random-effects logistic meta-regression.

RESULTS

Based on 33 studies (LR in 1,506 of 28,162), the odds of LR were associated with margin status [model 1: odds ratio (OR) 1.96 for positive/close vs negative; model 2: OR 1.74 for close vs. negative, 2.44 for positive vs. negative; (P < 0.001 both models)] but not with margin distance [model 1: >0 mm vs. 1 mm (referent) vs. 2 mm vs. 5 mm (P = 0.12); and model 2: 1 mm (referent) vs. 2 mm vs. 5 mm (P = 0.90)], adjusting for study median follow-up time. There was little to no statistical evidence that the odds of LR decreased as the distance for declaring negative margins increased, adjusting for follow-up time [model 1: 1 mm (OR 1.0, referent), 2 mm (OR 0.95), 5 mm (OR 0.65), P = 0.21 for trend; and model 2: 1 mm (OR 1.0, referent), 2 mm (OR 0.91), 5 mm (OR 0.77), P = 0.58 for trend]. Adjustment for covariates, such as use of endocrine therapy or median-year of recruitment, did not change the findings.

CONCLUSIONS

Meta-analysis confirms that negative margins reduce the odds of LR; however, increasing the distance for defining negative margins is not significantly associated with reduced odds of LR, allowing for follow-up time. Adoption of wider relative to narrower margin widths to declare negative margins is unlikely to have a substantial additional benefit for long-term local control in BCT.

Meta-analysis of the impact of surgical margins on local recurrence in women with early-stage invasive breast cancer treated with breast-conserving therapy

PURPOSE

There is no consensus on what constitutes adequate negative margins in breast-conserving therapy (BCT). We review the evidence on surgical margins in BCT for early-stage invasive breast cancer.

METHODS

Meta-analysis of studies reporting local recurrence (LR) relative to quantified final microscopic margin status and the threshold distance for negative margins. The proportion of LR was modelled using random effects logistic meta-regression.

RESULTS

Based on 21 studies (LR in 1,026 of 14,571 subjects) the odds of LR were associated with margin status [model 1: odds ratio (OR) = 2.02 for positive/close versus negative; model 2: OR = 1.80 for close versus negative, 2.42 for positive versus negative (P<0.001 both models)] but not with margin distance [1mm versus 2mm versus 5mm (P > 0.10 both models)], adjusting for median follow-up time. However, there was weak evidence in both models that the odds of LR decreased as the threshold distance for declaring negative margins increased. This bordered significance in model 2 [OR for 1mm, 2mm, 5mm: 1.0, 0.75, 0.51 (P = 0.097 for trend)], and was not significant in model 1 [OR for 1mm, 2mm, 5mm: 1.0, 0.85, 0.58 (P = 0.11 for trend)] but was evident when one study (of women ≤ 40 years) was excluded from this model [OR for 1mm, 2mm, 5mm: 1.0, 0.72, 0.52 (P = 0.058 for trend)]: this trend was rendered insignificant by adjustment for the proportion of subjects receiving a radiation boost or the proportion of subjects receiving endocrine therapy.

CONCLUSIONS

Margin status has a prognostic effect in all women treated for invasive breast cancer; increasing the threshold distance for declaring negative margins is weakly associated with reduced odds of LR, however adjustment for covariates (adjuvant therapy) removes the significance of this effect. Adoption of wider margins, relative to narrower widths, for declaring negative margins is unlikely to a have substantial additional benefit for long-term local control in BCT.

Do all patients require radiotherapy after breast-conserving surgery?

Radiotherapy following breast conservation is routine in the treatment of breast cancer. This creates a large demand for radiotherapy services with implicit cost effects and potential morbidity to patients. Radiotherapy is administered to decrease local recurrence, but is radiotherapy required for all breast cancers? A literature search using the Medline and Ovid databases was conducted between 1965 and 2010 using the terms ‘role of radiotherapy’, ‘early breast cancer’, and omission of radiotherapy’. Papers with clinical trials published in English in adult humans were included. Fourteen randomized controlled trials were included. Local recurrence rates range from 0.8–35% in patients in whom radiotherapy was omitted. Low risk characteristics include older age, small tumor size, no lymphovascular invasion and low to moderate grade. At present, there is no clearly defined low risk group of patients in whom radiotherapy can be omitted.