Maximum tumor diameter and renal function can predict the declining surface dose rate after 177Lu-Dotatate: preliminary results of single institution in Japan

Takashi Ono; Mayumi Ichikawa; Takeo Tanada; Chika Kanezawa; Hiraku Sato

doi:10.1007/s11604-024-01585-5

Maximum tumor diameter and renal function can predict the declining surface dose rate after ¹⁷⁷Lu-Dotatate: preliminary results of single institution in Japan

Jpn J Radiol. 2024 May 10. doi: 10.1007/s11604-024-01585-5. Online ahead of print.

Authors

Takashi Ono¹, Mayumi Ichikawa², Takeo Tanada³, Chika Kanezawa³, Hiraku Sato³

Affiliations

¹ Department of Radiation Oncology, Faculty of Medicine, Yamagata University, 2-2-2, Iida-Nishi, Yamagata, 990-9585, Japan. abc1123513@gmail.com.
² Department of Radiation Oncology, Faculty of Medicine, Yamagata University, 2-2-2, Iida-Nishi, Yamagata, 990-9585, Japan.
³ Department of Radiology, Yamagata University Hospital, 2-2-2, Iida-Nishi, Yamagata, 990-9585, Japan.

PMID: 38727960
DOI: 10.1007/s11604-024-01585-5

Abstract

Purpose: This study aimed to develop a user-friendly prediction formula for dose rate adjustment after initial ¹⁷⁷Lu-Dotatate therapy from a prospective observational study of patients.

Materials and methods: This study included consenting patients in a prospective observational study who underwent their first treatment in four cycles of ¹⁷⁷Lu-Dotatate treatment at our hospital between January 2022 and February 2024. All patients received 7.4 GBq of ¹⁷⁷Lu-Dotatate. The prediction formula was derived from the regression analysis of tumor-related factors and renal function. Creatinine clearance was estimated using the Cockcroft-Gault equation in this study for renal function.

Results: Among the 13 patients (seven males, six females, median age: 59 years), logarithmically transformed total tumor volume (cc) and maximum tumor diameter (mm) of primary tumors or metastases showed strong correlations (p < 0.001, R² = 0.897). As such, the maximum tumor diameter was used as the tumor parameter in the prediction formula. Additionally, maximum tumor diameter and creatinine clearance showed strong (p < 0.001, R² = 0.768) and moderate (p = 0.013, R² = 445) correlations, respectively, with the ratio of the dose rate 5.5-h post-administration to the dose rate immediately post-administration (%) at 1 m from the body surface. The resulting formula, 51.4 + 0.360 × maximum tumor diameter (mm) - 0.212 × creatinine clearance (ml/min), demonstrated an extremely strong correlation (p < 0.001, R² = 0.937).

Conclusion: The present study showed that the maximum tumor diameter and renal function affected the declining the dose rate of patients surface after ¹⁷⁷Lu-Dotatate, which can inform post-administration dose rate management and potentially facilitate outpatient treatment in Japan.

Keywords: 177Lu-Dotatate; Dose rate; Peptide receptor radionuclide therapy; Renal function; Tumor diameter.