Relationship of margin status and radiation dose to recurrence in post-operative vulvar carcinoma.

OBJECTIVE

To evaluate the effect of margin status and radiation dose in patients treated with radiation therapy (RT) for vulvar cancer. Clinical outcomes included vulvar recurrence (VR), relapse-free survival (RFS) and overall survival (OS).

METHODS

We retrospectively reviewed the records of 300 patients with Stage I-IVA vulvar cancer treated between 1988 and 2009. Slides were reviewed and margin status was scored as negative (≥ 1 cm), close (<1cm) or positive after formalin fixation. Cox proportional hazards models were constructed to determine significant prognostic factors for vulvar relapse.

RESULTS

Of 205 eligible patients, 69 (34%) had negative surgical margins, 116 (56%) had close margins and 20 (10%) had positive margins. Median follow-up time was 49 months. The 4-year RFS rate was 53% and OS was 73%. Of 78 recurrences, 62 had the vulva as the first site of recurrence. The 4-year rates of freedom from vulvar recurrence were 82%, 63% and 37% for those with negative, close and positive margins, respectively (p for trend=0.005). On multivariate analysis, close margins (HR=3.03, 95% CI 1.46-6.26) and positive margins (HR=7.02, 95% CI 2.66-18.54) were associated with a significantly increased risk of vulvar relapse. Those who received a dose ≥ 56 Gy had a lower risk of relapse than those who received ≤ 50.4 Gy (p<0.05). Though recurrences were noted with margins up to 9 mm, the highest risk of vulvar recurrence was associated with margins ≤ 5 mm (p=0.002).

CONCLUSIONS

Close or positive margins were associated with a significantly increased risk of vulvar recurrence. Radiation with a dose ≥ 56 Gy may decrease the risk of vulvar recurrence.