Abstract

Roberta Tummineri¹, Andrei Fodor¹, Flavia Zerbetto¹, Ariadna Sanchez Galvan², Stefano Lorenzo Villa², Simone Baroni², Giuseppina Mandurino², Pietro Pacifico², Chiara Deantoni¹, Paola Mangili³, Antonella Del Vecchio³, Nadia Gisella Di Muzio⁴

¹IRCCS San Raffaele Scientific Institute, Radiation Oncology, Milano, Italy; ²Milano-Bicocca University, Radiation Oncology, Milano, Italy; ³IRCCS San Raffaele Scientific Institute, Medical Physics, Milano, Italy; ⁴IRCCS San Raffaele Scientific Institute - Vita e Salute San Raffaele University, Radiation Oncology, Milano, Italy

Radiotherapy plays an important role in the management of vulvar cancer, a malignancy affecting older women, which are generally frail and therefore very disturbed by side effects. Here we report outcomes and toxicities in vulvar cancer patients (pts) treated with Image-Guided helical/volumetric intensity modulated radiotherapy (IG-IMRT) in our Institute.

From August 2006 to May 2020, 25 pts diagnosed with vulvar cancer were treated with IG-IMRT. Histology was: squamous cell carcinoma in 22 pts, adenocarcinoma in 2 pts, and Paget’s disease in 1 patient. Median age was 75 (32-91) years, 76% of pts were older than 70 years. Thirteen pts (52%) underwent postoperative RT for FIGO stages: pTis 1 patient (8%), IB 4 pts (31%), IIIA 4 pts (31%), IIIC 3 pts (23%), and IVB 1 patient (7%). Surgical margins were: R1 in 1 patient (8%), <1mm in 6 pts (46%), R0 in 6 pts (46%). Four pts (16%) underwent radical RT (equally distributed in FIGO stages IB, IIIA, IIIB, and IVB). Eight pts (32%) were treated with salvage RT on recurrences after surgery. Clinical tumor volume (CTV) was delineated on CT scan (48%) or FDG-PET/CT (52%) including vulva, inguinal and pelvic lymph nodes (LN). Median prescribed dose to PTV was 50.4 (45-62.5) Gy. Simultaneous integrated boost (SIB) was delivered in 13 pts to a median dose of 61.2 (58.8-64.5) Gy on positive FDG-PET/CT positive LN or tumor. Ten pts received sequential boost: 4 with photons, 6 with electrons to a median dose of 14.4 (9-16) Gy. Three pts received concomitant cisplatin. RT was delivered with helical or volumetric IMRT and daily IGRT was performed.

Median follow-up was 18 (2.4-95.4) months. Acute and late toxicities were graded according RTOG scale (see Table 1). Seven pts had a median of 8 (2-14) days of treatment interruption due to acute toxicity (4 pts with sequential boost, only 1 patient with SIB, 2 pts with concomitant CT). All pts finished the prescribed treatment. Local control, evaluated with FDG-PET/CT, was achieved in 54.5% of pts. Eight pts (36%) presented local relapse (4 vulvar and 4 LN) and 4 pts (18%) distant progression (LN and/or lung metastasis). Average time to local and distant progression were 9.4 and 10 months respectively. Average overall survival (OS) was 29 months. Pts treated with adjuvant RT had better outcomes with a median OS of 33.9 months, followed by salvage RT with 28.3 months. Radical RT OS was only 6.6 months, though the median age of pts was 86.3 (79.5-90.2) years.

IG-IMRT for vulvar cancer is feasible and SIB seems to reduce the treatment interruptions due to skin toxicity. A randomized study is needed to confirm toxicity reduction with SIB.