B45: Thyroid atrophy in patients receiving Sunitinib or Pazopanib for the treatment of advanced renal cell carcinoma: A common but under-reported toxicity.

Georgina Elizabeth Wood2,James Albert Bennett1,2,Eirini Vrentzou1,Arnold Eric Conrad Drury1,Thomas Richard Geldart1,2

1The Royal Bournemouth and Christchurch Hospitals NHS Foundation Trust, Bournemouth, UK,2Poole Hospital NHS Foundation Trust, Poole, UK

Presenting date: Tuesday 3 November
Presenting time: 12.20-13.10

Background

Sunitinib (Su) and Pazopanib (Pa) represent standard first line treatment for patients with metastatic Renal Cell Carcinoma (mRCC). Hypothyroidism is commonly reported but the incidence of thyroid atrophy is unknown and rarely reported.

Method

We retrospectively reviewed case notes, thyroid function tests and serial CT images from all patients undergoing at least 6 months first line treatment for mRCC with Su or Pa between 1.5.07 and 31.5.14. Thyroid volumes (mm3) were evaluated using Livewire segmentation at a matched level for all scans. Change in size over time was estimated. Baseline demographics, Heng prognostic group and outcomes were collated.

Results

66 patients were identified that met all study entry criteria. 20% had good (G), 53% intermediate (I) and 27% poor (P) prognostic disease by Heng criteria at initiation of treatment. 80% received Su and 20% Pa.

At data cut-off, 30% remain on first line treatment. 56% have died. Median time on treatment was 20 months. Median overall survival was 39 months by Kaplan-Meier analysis. 67% had documented hypothyroidism during treatment. 5% did not have any documented thyroid function results. Changes in thyroid volume were grouped into stable (S; +20% to -20% compared to baseline), moderate atrophy (Mo; > 20-50%) and major atrophy (Ma; > 50%). Overall, 38% developed Mo (18%) or Ma (20%) reduction in thyroid volume (range 21-82%). Median treatment duration in the Ma group was over 2.5 times that of the S group (48 v 18 months; p = 0.01), with maximal atrophy seen late in the course of treatment (69% of patients had received > 80% delivered treatment).

Conclusion

Thyroid atrophy is common and is seen in more than one-third of patients receiving first line treatment with Su or Pa for over 6 months. There is an increased incidence of thyroid atrophy with longer exposure to treatment.