Session Item

To compare clinical outcomes of intensity modulated radiation therapy (IMRT) alone vs IMRT+ brachytherapy in patients with early staged oropharyngeal squamous cell cancers (OSCC).

Newly diagnosed patients with  biopsy proven stage I and II OSCC of were randomized to IMRT alone vs IMRT + brachytherapy. Randomization was done using computer generated block randomization (1:1) at a single centre. All patients received IMRT to a dose of 50Gy/25#/5 weeks in phase I. In phase II patients in the IMRT arm received 20Gy/10#/2 weeks and in the brachytherapy arm received high dose rate brachytherapy to a dose 21Gy/7fractions/2 fractions per day. Primary endpoint of the trial was reduction in xerostomia at 6 months. Evaluation of xerostomia was done using T99 salivary scintigraphy, RTOG toxicity criteria, EORTC quality of life questionnaire and xerostomia questionnaire (XQ) at 3, 6, 12 and 24 months. Reduction in salivary function using scintigraphy was quantified by salivary excretion fraction (SEF) ratio. Post treatment SEF ratio <45% was considered as severe salivary toxicity. Secondary endpoints were local control (LC), disease free survival (DFS) and overall survival (OAS).

Between November 2009 to January 2020, 90 patients were randomized to IMRT (N=46) or IMRT plus brachytherapy (N=44).  Seven patients in the brachytherapy arm could not receive brachytherapy (technical feasibility-5, unfit for anesthesia -2) and were treated with IMRT. The analysis was done both by  intention to treat and per protocol.
At 6 months, SEF <45%  for ipsilateral parotid was observed in 15.2% patients in brachytherapy arm while it was seen in 43.8% patients in IMRT arm (p<0.01)  with similar trend at 12 and 24 months (p<0.01) (Fig 1).  For contralateral parotid at 6 months SEF <45% was observed in 12% in brachytherapy arm while it was 25% in IMRT arm (p=0.18) with similar trend at 12, 24 months (p=0.13). At 6 months RTOG Grade ≥ 2 xerostomia  was  4% in brachytherapy arm while it was 12.5% in IMRT arm (p=0.33). RTOG Grade ≥ 2 xerostomia  over the time period was 11. 4% in brachytherapy arm while it was 28.3% in IMRT arm (p=0.04). The mean xerostomia score of XQ at 6 months was 28 for brachytherapy and 37 for IMRT with similar trend at 12 and 24 months (p=0.02).
At a median follow up of 42.5 months the 2 year LC was 69% in brachytherapy arm and 61.4% in IMRT arm (p=0.23). There was a trend towards improved LC with brachytherapy in per protocol analysis (74.4% vs 58.7% p=0.07). The 2 year OAS was 70.3% in brachytherapy arm and 72.6% in IMRT arm (p=0.39)

Figure 1. Xerostomia by Salivary scintigraphy for ipsilateral parotid

Addition of brachytherapy to IMRT for early stage oropharyngeal cancers results in significant reduction in xerostomia and should be considered as the standard of care in suitable cases.