Introduction
The initial results and clinical feasibility of the novel hybrid combined intracavitary and interstitial Venezia applicator for cervical cancer brachytherapy have been recently reported.Reference Walter, Maihöfer and Schüttrumpf 1 The results reflect the improved conformity and dose delivery that is made possible by simultaneously combining intracavitary and interstitial brachytherapy in a single fraction. The issue is of particular importance in locally advanced cervix cancer where tumour volume after completion of external beam radiotherapy is considerably large and may extend to the parametria, vagina and uterine body.
Cancer of the cervix continues to remain a major health concern among women in the developing world. Despite the decreasing trend in the incidence of cervix cancer in India, global cancer statistics reveal that India is the single major contributor to cases of cervical cancer in the Southeast Asian region, with one of the highest incidence and mortality rates from the disease.Reference Ferlay, Soerjomataram and Ervik 2 , Reference Bruni, Barrionuevo-Rosas and Albero 3 Most cases present at a locally advanced stage, when the gold standard of treatment is definitive chemoradiation. Owing to the larger tumour volume in these stages, intracavitary brachytherapy alone offers inadequate target coverage, necessitating additional interstitial brachytherapy. Suboptimal dosing of the target volume has been associated with inferior outcomes and the Groupe Européen de Curiethérapie -European SocieTy for Radiotherapy & Oncology (GEC-ESTRO) recommendations advocate achieving at least 85 Gy to 90% of the high-risk clinical target volume (HRCTV D 90>85 Gy) while respecting the tolerance of the organs at risk (OARs).Reference Pötter, Haie-Meder and Van Limbergen 4
The Venezia applicator from Elekta (Stockholm, Sweden) has addressed this issue, providing the benefits of a central high-dose region offered by the intracavitary tandem and ovoids (assembled to form a ring), in addition to the benefits of a wider volume coverage by placing a selection of holes for interstitial needle placement on the ring and also on the click on template. A cylinder cap has been additionally integrated into the design for improved dosimetry in cases where the upper vaginal wall is involved. Overall, the applicator is a versatile, ergonomically designed instrument for treating locally advanced cervix cancer in particular, to achieve the goal of HRCTV D 90>85 Gy while respecting dose constraints of the OARs.
Patients and Methods
At our institute, retrospective data were analysed from 66 selected patients who had received simultaneous combined intracavitary and interstitial brachytherapy following chemoradiation during February 2007 to March 2008. All women had locally advanced cervix cancer (stages IIB–IVA). The chosen patients had received pelvic chemoradiation with telecobalt (Theratron 780C, Theratronics, Canada) using parallel opposed antero-posterior and postero-anterior fields with weekly concomitant Cisplatin at a dose of 40 mg/m2. A brachytherapy preplanning computed tomography (CT) scan was performed, along with a gynaecological examination to determine the extent of tumour after pelvic chemoradiation was completed. All women had been treated using the GammaMed Plus high dose rate (HDR) Ir192 brachytherapy source (Varian Medical Systems, Inc., Palo Alto, CA, USA). Applications were performed using an intrauterine tandem combined with Martinez Universal Perineal Template (MUPIT)/Syed Neblett template-guided interstitial needles, with the objective of adequate target coverage. Position and length of needle placement was recorded at the first session to ensure reproducibility in subsequent sessions. Clinical target volume was contoured based on information from the preplanning CT scan combined with post chemoradiation gynaecological examination findings. Brachytherapy treatment delivery was planned using post insertion CT scans and all plans were evaluated slice by slice to ascertain adequate target coverage while avoiding hotspots in any OARs. All patients in the chosen group received HDR brachytherapy weekly at 9 Gy/fraction for two fractions. Graphical optimisation was used for planning the brachytherapy treatments. Dose volume histograms were individually analysed to ensure adherence to recommended standards of conformity and dose delivery.
Results
The patients were aged between 29 and 63 years (median 48 years); 58/66 (87.8%) of them had stage IIIB disease. All women had uniformly received pelvic chemoradiation with the same beam energy and concomitant chemotherapy schedule. Brachytherapy involved a combined intracavitary and interstitial application in all patients. Analysis of the dose volume parameters showed the mean HRCTV D 90 to be 88.7 Gy (range 76.9–94.1 Gy) with a mean V 150 of 61.2 cc (range 39.4–71.4 cc). For the OARs, the mean rectum D 2cc was found to be 60.1 Gy (range 58.4–66.3 Gy) and the mean bladder D 2cc was 78.9 Gy (range 77.4–89.2 Gy).
Discussion
Acceptable coverage was achieved in each fraction with reasonable OAR doses using a hybrid combined intracavitary and interstitial application among these patients at our institute. The application utilised only those resources that were available at that point in time, such as the perineal templates, CT compatible interstitial needles and an appropriate intrauterine tandem. No extra funding was available for acquiring a hybrid combined intracavitary and interstitial applicator such as the Vienna applicator during that period.
We speculate that a number of factors may have contributed to the favourable dose volume parameters in these patients. First, graphical optimisation contributed to improved conformity and target coverage. Second, rectal doses were probably kept lower by the absence of the ovoids/ring applicator during treatment. Lastly, our patient group was unique in that all of them were of Southeast Asian (mainly Indian) ethnicity. Studies on pelvimetry and functional anatomy have demonstrated significant differences among females, based on their ethnicity.Reference Handa, Lockhart and Fielding 5 , Reference Sen 6 Smaller pelvic dimensions in women of Southeast Asian ethnicity could have had an impact on the spatial positioning of the organs and geometry in this cohort.
In this communication we share our experience because brachytherapy services are cost and labour-intensive. For those working in limited-resource settings, there is a scarcity of funding and resources. Centres functioning under financial and resource constraints may not have immediate access to the Venezia applicator until additional funding is made available. These findings from our institute demonstrate that it may be possible to achieve acceptable dose volume parameters in brachytherapy treatments of locally advanced cervical cancer using an intrauterine tandem combined with MUPIT/Syed Neblett template-guided interstitial needles, until appropriate technology is made available.
Conflicts of interest
None.
Ethical statement
The authors assert that all procedures contributing to this work comply with the Helsinki Declaration of 1975, as revised in 2008, and has been approved by the Institutional Ethical Committee of Medical College Hospitals, Kolkata, India.
Acknowledgements
None.
