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An Analytical Study to Determine Dose-Volume Threshold for Radiation Induced Hypothyroidism
Kumar Pravesh1, Pooja Sethi1, Sadish Kumar Kamalanathan2
1Department of Radiation Oncology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India.
Asian Pacific Journal of Cancer Prevention : APJCP
|November 29, 2023
Summary
Radiation dose thresholds for the thyroid gland, specifically mean dose (Dmean) under 28 Gy and V40 under 49%, can help prevent radiation-induced hypothyroidism (RIHT) in cancer patients after neck irradiation.
Area of Science:
- Radiation oncology
- Endocrinology
- Medical physics
Background:
- Neck irradiation for cancer treatment can lead to radiation-induced hypothyroidism (RIHT).
- Identifying predictive dose-volume thresholds is crucial for mitigating this side effect.
Purpose of the Study:
- To determine radiation dose-volume thresholds for predicting hypothyroidism in cancer patients post-neck irradiation.
- To identify risk factors associated with the development of RIHT.
Main Methods:
- Cross-sectional follow-up study of 120 cancer patients who received neck irradiation (3D-CRT or IMRT).
- Thyroid dose-volumetric analysis performed post-radiotherapy (minimum six months follow-up).
- Analysis included mean thyroid dose (Dmean) and volume receiving 40 Gy (V40).
Main Results:
- 40% of patients developed RIHT (25.8% clinical, 14.2% subclinical).
- Significant risk factors for RIHT included Dmean >28 Gy, V40 >49%, and age <50 years.
- Hypothyroidism onset peaked around two years post-irradiation.
Conclusions:
- Thyroid gland Dmean <28 Gy and V40 <49% are potential dose-volume thresholds to prevent RIHT.
- These thresholds can aid in optimizing radiotherapy planning to reduce hypothyroidism risk.
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