Counterpoint: Time to retire the parametrial boost

Abstract

For decades, treatment of locally advanced cervical cancer has been dominated by whole pelvic external beam radiotherapy (EBRT) combined with Point A-based intracavitary (IC) brachytherapy (BT). As reflected in this point/ counterpoint discussion, parametrial boost (PMB) by EBRT is still used to treat disease at the pelvic side wall, which is out of reach from standard IC BT (1). Traditionally, rectangular anterior posterior-posterior anterior (AP-PA) fields with a midline block have been used, but more advanced PMB techniques including step wedges to adjust for the BT dose gradient or conformal midline blocking according to a chosen isodose of BT have also been described (1, 2). There is little consensus as to the indications, optimal technique, or dose of PMB (3). Quite heterogeneous PMB doses have been reported, such as 5e20 Gy to the parametria on top of 40e45 Gy whole pelvic EBRT depending on International Federation of Gynecology and Obstetrics (FIGO) stage (1). A recent patterns of care study found that most commonly added PMB dose currently after 45 Gy whole pelvic EBRT (4) is 5.4 Gy. Based on superior doseevolume parameters (5e9) and excellent clinical results (10e13), image-guided adaptive brachytherapy (IGABT) performed according to the Groupe Europ een de Curieth erapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) guidelines (14, 15) is increasingly becoming the standard of care for the treatment of locally advanced cervical cancer gradually replacing prescription to Point A. Also, the American Brachytherapy Society is endorsing IGABT for cervix according to the GEC-ESTRO guidelines. When compared with historical series, IGABTprovide higher rates of local tumor control in advanced stage disease also with extensive parametrial