18. Primary vaginal cancer and vaginal recurrences - The GEC-ESTRO Handbook of Brachytherapy

Primary vaginal cancer and vaginal recurrences

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THE GEC ESTRO HANDBOOK OF BRACHYTHERAPY | Part II Clinical Practice Version 1 - 01/09/2023

Figure 1. Schematic diagram with corresponding T2WI MRI of the anatomy of the vagina and adjacent tissues in the axial (mid and lower vagina) and sagittal planes. Adopted and re-used with permission from Albuquerque et. al. [2].

4. PATHOLOGY

The lymphatic drainage of vaginal tumours is correlated to the double embryologic origin of the vagina from the Müllerian canal and urogenital sinus. Its drainage is via the lymphatic vessels in the vaginal submucosa to the iliac and obturator nodes for the upper two thirds of the vagina, and to the hypogastric and inguinal nodes for the lower third; the drainage of the posterior wall and rectovaginal septum is to the sacral nodes, and in some cases the mesorectum [5]. Due to its superior soft-tissue contrast, magnetic resonance imaging (MRI) is the best imaging modality to display the anatomy of the vagina, especially in comparison to computed tomography (CT)[6]. In addition, ultrasound/sonography (US) also has a good soft-tissue contrast and could be helpful in the operating room (OR) to localize the vaginal tumour and guide the implantation of the applicator and interstitial needles [7]. Minimal requirements to visualize the vaginal tumour are the acquisition of three orthogonal (axial, sagittal and coronal) T2 weighted series, preferably supplemented with functional series such as diffusion-weighted images (DWI). On T2-weighted images a vaginal tumour is usually demarked as an intermediate to hyper-intense lesion [2, 6]. The application of intravaginal gel could be considered for better visualisation of the tumour.

Primary vaginal cancer resembles the aetiology of cervical cancer as the majority of cases are HPV-positive squamous cell carcinomas (80 - 85%)[8]. The other known histological subtypes are adeno- or adenosquamous carcinoma (10 - 15%), sarcoma and melanoma (2 - 3%), and others like clear cell carcinomas from diethylstilbestrol (DES) application (1 - 2%)( https://www. uptodate.com/contents/vaginal-cancer). In case of a vaginal recurrence of a different origin like cervical, endometrial, rectal or ovarian cancer, the histology resembles the primary tumour.

5. WORK UP

Staging for primary vaginal cancer is defined using the TNM (Union for International Cancer Control) and FIGO (The International Federation of Gynaecology and Obstetrics) classification (Table 1)[9, 10]. The diagnostic work up consists of a combination of careful gynaecological examination with biopsies and imaging. It is important to exclude a tumour arising elsewhere and involving the vagina, or vaginal metastases from gynaecological tumours