Management of Positive Margins After Lung Resection/Bilobectomy
When clear margins are not achieved during lung resection or bilobectomy, re-resection should be attempted whenever feasible to achieve R0 status, as microscopic residual disease significantly worsens survival in early-stage disease; if re-resection is not possible, adjuvant radiotherapy is indicated for positive margins. 1
Immediate Intraoperative Management
Intraoperative margin assessment using frozen section or staple line cytology can be performed, though patients with positive cytology typically undergo immediate further resection during the same procedure. 1
For sublobar resections, aim for margins >2 cm or at least equal to the tumor diameter (margin-to-tumor ratio ≥1.0) to minimize local recurrence risk, as margins <1 cm are associated with 25% local recurrence versus 6.2% for adequate margins. 1
Avoid extensive tissue undermining or reconstruction until negative margins are confirmed histologically, as this can displace potentially positive margins and complicate re-excision interpretation. 1
Postoperative Management Based on Margin Status
R1 Resection (Microscopic Positive Margins)
The management strategy depends critically on the location and stage of residual disease:
For carcinoma in situ (CIS) at the bronchial margin: Conservative surveillance with frequent bronchoscopy is appropriate, as survival is comparable to R0 resection. 2
For microscopic mucosal residual disease in stage I-II NSCLC: Further treatment is mandatory, as 5-year survival drops to 0-20% compared to R0 resection due to high local recurrence rates. 2, 3
For peribronchial residual disease: Prognosis is particularly poor (1-year survival 20-50%, 5-year survival 0-20%) because 75-85% have associated mediastinal lymph node metastases. 2
For stage III NSCLC with positive margins: The negative impact is limited since patients typically die from distant metastases before local recurrence occurs, making aggressive local therapy less beneficial. 2
Re-Resection Considerations
Re-excision of the surgical bed should be performed if adequate margins can be achieved with acceptable morbidity, particularly for stage I-II disease where local control directly impacts survival. 1
Full restaging with MRI of the surgical bed is required to assess for gross residual disease before planning re-resection. 1
If re-excision would result in considerable morbidity (such as requiring pneumonectomy after bilobectomy) or is unlikely to achieve complete clearance, observation or radiotherapy are alternative strategies. 1
Bilobectomy after neoadjuvant chemoradiotherapy carries particularly high operative mortality (8.7% at 30 days, 13% at 90 days), which must be weighed against the benefits of achieving clear margins. 4
Adjuvant Therapy Options
Radiotherapy
Postoperative radiotherapy is indicated for patients with positive resection margins when further resection is not feasible, as there is evidence of benefit in this specific scenario. 1
However, routine postoperative radiotherapy following complete R0 resection is not recommended and may be harmful in stage I-II disease. 1, 5
Brachytherapy
Intraoperative ¹²⁵I brachytherapy mesh placement can be considered for sublobar resections with anticipated close margins, reducing local recurrence from 17-19% to 2-3% in retrospective series. 1, 6
However, the randomized ACOSOG Z4032 trial showed no significant reduction in local recurrence with brachytherapy (HR 1.01), possibly because surgeons achieved better margins when participating in the trial. 7
Brachytherapy may still have a role in patients with positive staple line cytology, where trends favored the brachytherapy arm despite small numbers. 7
Systemic Therapy for EGFR-Mutant NSCLC
For EGFR-mutant stage IB-IIIA NSCLC with R1 resection, adjuvant osimertinib may be considered via extrapolation from ADAURA trial data, particularly given the high risk of relapse with positive margins. 1
Adjuvant platinum-based chemotherapy remains strongly recommended for stage IB-IIIA disease regardless of margin status or addition of targeted therapy. 1
Critical Pitfalls to Avoid
Do not perform wide undermining or complex reconstruction before confirming negative margins, as this conceals residual tumor and complicates interpretation of subsequent re-excisions. 1
Do not assume all R1 resections have the same prognosis—CIS at the bronchial margin has excellent outcomes with surveillance alone, while peribronchial residual disease is nearly uniformly fatal without additional treatment. 2
The 5-10% rate of patients found inoperable at surgery should not be exceeded; rates above this suggest inadequate preoperative staging. 1, 5
Recognize that bilobectomy carries mortality rates approaching pneumonectomy (8.7% vs 10.7% at 90 days post-neoadjuvant therapy), making the risk-benefit calculation for re-resection particularly challenging. 4