Radiation dose profile in 125I brachytherapy: an 8-year review

Clinical efficacy of CT-guided 125I brachytherapy in patients with local residual or recurrent hepatocellular carcinoma after thermal ablation

OBJECTIVES

Treatment methods of local residual or recurrent hepatocellular carcinoma (HCC) after thermal ablation are limited. Therefore, our study aimed to explore the efficacy and prognostic factors of ¹²⁵I brachytherapy for local residual or recurrent lesion after thermal ablation.

METHODS

A total of 114 patients with 212 local residual or recurrent HCC tumors after thermal ablation underwent ¹²⁵I brachytherapy. Local progression-free survival (LPFS) and prognostic factors were analyzed by Kaplan-Meier curves and the Cox model.

RESULTS

After a 6-month follow-up, the percentage of patients who achieved complete response (CR), partial response (PR), and stable disease (SD) was 57%, 13.2%, and 5.2%, respectively. The 1-, 2-, and 3-year LPFS rates were 58.7%, 50.0%, and 41.2%, respectively. Portal vein tumor thrombus (PVTT) (p = 0.03), the number of intrahepatic tumors (p = 0.01), and AFP level (p = 0.02) were independent risk factors for local tumor progression (LTP). The median LPFS in patients without PVTT (22 months) was much longer compared to those with PVTT (10 months). The median LPFS in patients with less than three intrahepatic lesions improved from 17 to 24 months. The median LPFS was only 5 months in the high AFP group, but was prolonged with a decrease in AFP level (24 months). No severe complications were recorded. All complications were controllable and treatable.

CONCLUSIONS

CT-guided ¹²⁵I brachytherapy was a safe and effective treatment for patients with local residual or recurrent HCC after thermal ablation to improve local control rate.

Feasibility and clinical value of CT-guided 125I brachytherapy for metastatic soft tissue sarcoma after first-line chemotherapy failure

PURPOSE

To evaluate the feasibility and usefulness of computed tomography (CT)-guided iodine¹²⁵ (¹²⁵I) brachytherapy for patients with metastatic soft tissue sarcoma (STS) after first-line chemotherapy failure.

METHODS

We recruited 93 patients with metastatic STS who had received first-line chemotherapy 4-6 times but developed progressive disease, from January 2010 to July 2015; 45 patients who had combined ¹²⁵I brachytherapy and second-line chemotherapy (Group A), and 48 patients who received second-line CT only (Group B).

RESULT

In Group A, 49 ¹²⁵I seed implantation procedures were performed in 45 patients with 116 metastatic lesions; the primary success rate was 91.1% (41/45), without life-threatening complications. Local control rates at 3, 6, 12, 24 and 36 months were 71.1%, 62.2%, 46.7%, 28.9% and 11.1% for Group A, and 72.9%, 54.2%, 18.8%, 6.3% and 0% for Group B. Mean progression-free survival differed significantly (Group A: 7.1±1.3 months; Group B: 3.6 ±1.1 months; P<0.001; Cox proportional hazards regression analysis), but overall survival did not significantly differ (Group A: 16.9 ±5.1 months; Group B: 12.1 ± 4.8 months). Group A showed better symptom relief and quality of life than Group B.

CONCLUSION

CT-guided ¹²⁵I brachytherapy is a feasible and valuable treatment for patients with metastatic STS.

KEY POINTS

• ¹²⁵ I brachytherapy is feasible and valuable for treating metastatic soft tissue sarcoma. • ¹²⁵ I brachytherapy represents a prominent activity in disease control. • ¹²⁵ I brachytherapy can achieve better symptom relief and quality of life.

I125 brachytherapy guided by individual three-dimensional printed plates for recurrent ameloblastoma of the skull base

Ameloblastoma is one of the most common benign odontogenic tumours of the mandible and the maxilla. Wide excision of the tumour is the first choice for treatment (except for unicystic ones). Patients with invaded margins or unresectable lesions may require radiotherapy. Today, permanent implantation of I¹²⁵ seeds is widely used in the treatment of cancer of the head and neck. We report a case of recurrent ameloblastoma of the base of the skull that was treated with I¹²⁵ brachytherapy. The outcome has been encouraging, with total disappearance of the tumour on positron emission tomography 18 months later.

Retinoblastoma

Retinoblastoma is the most common neoplasm of the eye in childhood, and represents 3% of all childhood malignancies. Retinoblastoma is a cancer of the very young; two-thirds are diagnosed before 2 years of age and 95% before 5 years. Retinoblastoma presents in 2 distinct clinical forms: (1) a bilateral or multifocal, heritable form (25% of all cases), characterized by the presence of germline mutations of the RB1 gene; and (2) a unilateral or unifocal form (75% of all cases), 90% of which are nonhereditary. The treatment of retinoblastoma is multidisciplinary and is designed primarily to save life and preserve vision.

Evaluation of two (125)I-radiolabeled acridine derivatives for Auger-electron radionuclide therapy of melanoma

We previously selected two melanin-targeting radioligands [(125)I]ICF01035 and [(125)I]ICF01040 for melanoma-targeted (125)I radionuclide therapy according to their pharmacological profile in mice bearing B16F0 tumors. Here we demonstrate in vitro that these compounds present different radiotoxicities in relation to melanin and acidic vesicle contents in B16F0, B16F0 PTU and A375 cell lines. ICF01035 is effectively observed in nuclei of achromic (A375) melanoma or in melanosomes of melanized melanoma (B16F0), while ICF01040 stays in cytoplasmic vesicles in both cells. [(125)I]ICF01035 induced a similar survival fraction (A50) in all cell lines and led to a significant decrease in S-phase cells in amelanotic cell lines. [(125)I]ICF01040 induced a higher A50 in B16 cell lines compared to [(125)I]ICF01035 ones. [(125)I]ICF01040 induced a G2/M blockade in both A375 and B16F0 PTU, associated with its presence in cytoplasmic acidic vesicles. These results suggest that the radiotoxicity of [(125)I]ICF01035 and [(125)I]ICF01040 are not exclusively reliant on DNA alterations compatible with γ rays but likely result from local dose deposition (Auger electrons) leading to toxic compound leaks from acidic vesicles. In vivo, [(125)I]ICF01035 significantly reduced the number of B16F0 lung colonies, enabling a significant increase in survival of the treated mice. Targeting melanosomes or acidic vesicles is thus an option for future melanoma therapy.

Cryosurgery in combination with brachytherapy of iodine-125 seeds for pancreatic cancer

A major limit of cryoablation is incomplete destruction of cells in the border zone of the cryogenic lesion in which the tissue temperature is warmer than (-)20 °C. The use of iodine-125 seed implantation is likely to be complementary to cryosurgery for treatment of pancreatic cancer. The procedure of cryosurgery and iodine-125 seed implantation is performed with percutaneous approaches under guidance of ultrasound and/or CT. The number of iodine-125 seeds implanted for every patient was 34 in median. Forty-nine patients with locally advanced pancreatic cancer received cryosurgery with combination of iodine-125 seed implantation. During a median follow-up of 18 months, the median of over all survival was 16.2 months. The 6-, 12-, 24- and 36-month overall survival rates were 94.9%, 63.1%, 22.8% and 9.5%, respectively. Compared with patients with cryosurgery alone, combination treatment shows higher the 6- and 12-month survival rates and longer the median survival.

Radiation dose to the surgeon during plaque brachytherapy

PURPOSE

To evaluate the radiation dose to a surgeon's hands during I eye plaque procedures.

METHODS

Sixteen consecutive patients with uveal melanomas were scheduled for eye plaque brachytherapy. The same surgeon wore thermoluminescent dosimeters on the dominant index finger and thumb while placing and removing the eye plaque to measure radiation dose. Additional laboratory experiments were performed to measure unobstructed (by surgical gloves or other parts of the hand) radiation exposure from a plaque.

RESULTS

Hand radiation doses during eye plaque brachytherapy are very low, but measurable, with plaques containing an average of 1.3 GBq of 125I.

CONCLUSION

Using these data, a surgeon would need to perform more than 1,000 cases each year to approach or exceed the annual regulatory radiation dose limits for the extremities.