Dose to the penile bulb and individual patient anatomy are predictive of erectile dysfunction in men treated with 125I low dose rate brachytherapy for localized prostate cancer

125I seed implantation for lymph node metastasis from radioactive iodine-refractory differentiated thyroid carcinoma: a study on short-term efficacy and dosimetry

Objective

To investigate the feasibility and evaluate the safety and effectiveness of Computed Tomography (CT) guided125I radioactive particle implantation for treating lymph node metastases in radioiodine-refractory differentiated thyroid cancer (RAIR-DTC). To verify the accuracy of the computerized three-dimensional treatment planning system (TPS) in treating lymph node metastasis using125I particle implantation at the dosimetric level.

Methods

A retrospective analysis was conducted on 42 patients with RAIR-DTC and lymph node metastases who were admitted to the General Hospital of the Northern Theater Command between December 2016 and January 2019. During this analysis, physicians utilized preoperative CT images to design an intraoperative plan using TPS. The dosimetric parameters of the postoperative plan were then compared to the preoperative plan. Additionally, this study examined the changes in tumor size and tumor-related marker Thyroglobulin (Tg) values in patients at 2, 6, and 12 months after the operation.

Results

The number of125I radioactive particles implanted in 42 patients was 226, with an average of 14.5 (range 2.0-30.0) particles implanted per lesion. The local remission rates were 97.62% (41/42), 88.10% (37/42), and 85.71% (36/42) at 2, 6, and 12 months postoperatively, respectively. The volume of the lesions was (4.44 ± 1.57) cm3, (4.20 ± 1.70) cm3, and (4.23 ± 1.77) cm3at 2, 6, and 12 months after treatment, respectively, which significantly decreased from the preoperative baseline level of (6.87 ± 1.67) cm3(t-values: 9.466, 9.923, 7.566, all P<0.05). The Tg levels were 15.95 (5.45, 73.93) μg/L, 8.90 (2.20, 39.21) μg/L, and 6.00 (1.93, 14.18) μg/L at 2, 6, and 12 months after treatment, respectively, which were significantly lower than the preoperative baseline levels of 53.50 (20.94, 222.92) μg/L (Z values: -5.258, -5.009, -4.987, all P < 0.001). Postoperatively, Delivered to 90% of the GTV(D90) was slightly lower than the prescribed dose in 95.23% (40/42) of patients, but the difference was not statistically significant [(12,378.8 ± 3,182.0), (12,497.8 ± 1,686.4) cGy; t=0.251, P>0.05], and postoperative dose parameters delivered to 100% of the gross tumor volume (GTV)(D100) (6,881.5 ± 1,381.8) cGy, the volume percentages of GTV receiving 150% of the prescribed dose(V150) (58.5 ± 18.40)%) were lower than the preoperative plan D100 (8,085.8 ± 2,330.0) cGy, V150 (66.5 ± 17.70)%; t-value=8.913 and 3.032, both P<0.05; the remaining indicators were not significantly different from the preoperative plan (the differences in the number of implanted particles, Planning Target Volume(PTV), the volume percentages of GTV receiving 100% of the prescribed dose(V100), Homogeneity Index(HI)were not statistically significant (t/Z = -0.593, -1.604, 1.493, -0.663, all P>0.05).

Conclusion

Referring to the TPS preoperative plan, the125I particle implantation therapy for RAIR-DTC lymph node metastasis can achieve the expected dose distribution, ensuring precise short-term local tumor control efficacy.

[Relationship between doses to anatomical structures and erectile dysfunction after radiotherapy for prostate cancer: A systematic review]

PURPOSE

During prostatic radiotherapy, damage to several anatomical structures could be the cause of erectile dysfunction: corpora cavernosa, internal pudendal arteries, penile bulb, and neurovascular bundles. Numerous studies have analysed the correlations between the dose received by these structures and erectile function. The objective of this article is to make a systematic review on current knowledge.

MATERIALS AND METHODS

A systematic review was performed in the Medline database using the search engine PubMed. Keywords for the search included: erectile dysfunction, penile bulb, corpora cavernosa, cavernosum, neurovascular bundles, radiation therapy, cancer, prostate cancer. The selected articles must study a correlation between erectile dysfunction and the dose received by anatomical structures. A total of 152 articles were identified. Of these 152 articles, 45 fulfilled the defined selection criteria.

RESULTS

For corpora cavernosa, seven studies were identified, only two studies demonstrated a significant correlation between the dose received by corpora cavernosa and the occurrence of erectile dysfunction. For penile bulb, only 15 of 23 studies showed a correlation. A mean dose on the penile bulb greater than 20Gy was found to be predictive of erectile dysfunction. None of the eight trials concerning neurovascular bundles succeeded to show a correlation between dose and erectile dysfunction. Only one study evaluated the relationship between the dose received by internal pudendal arteries and erectile dysfunction but was found to be negative. However, vessels-sparing studies showed good results on erectile function preservation without compromising the target volume.

CONCLUSION

We currently have little data to show a correlation between erectile dysfunction and sexual structures. It would be necessary to have additional prospective studies evaluating the impact of an optimization on these sexual structures on erectile dysfunction.

Acute and late side-effects after low dose-rate brachytherapy for prostate cancer; incidence, management and technical considerations

PURPOSE

To review common reported side effects and complications after primary LDR-BT (monotherapy) and discuss some of the technical aspects that could impact the treatment outcomes.

METHODS AND MATERIALS

A literature search was undertaken using medical subject headings (MeSH) complemented by the authors' personal and institutional expertise.

RESULTS

The reported incidence of acute and late grade 2 or above urinary, bowel and sexual side effects is very variable across the literature. The learning curve and the implant quality have a clear impact on the toxicity outcomes. Being aware of some of the technical challenges encountered during the procedure and ways to mitigate them could decrease the incidence of side effects. Careful planning of seed placement and seed deposition allow sparing of the organs at risk and a lower incidence of urinary and gastro-intestinal toxicity.

CONCLUSIONS

Low dose-rate brachytherapy remains a standard monotherapy treatment in the setting of favorable-risk prostate cancer. High disease control and low long-term toxicities are achievable in expert hands with a good technique.

Toxicity in patients treated with permanent prostate brachytherapy using intraoperatively built custom-linked seeds versus loose seeds

Purpose

Low-dose-rate brachytherapy (BT) with permanent iodine-125 radioactive seeds is a highly effective treatment option for low- and favorable intermediate-risk prostate cancer. However, optimal implantation is not always achieved due to edema or seeds loss. One way to improve seed placement is the use of stranded seeds called "intraoperatively built custom-linked seeds (IBCLS)" in an opposition to loose seeds (LS). To date, there are few data comparing toxicity rates between these two techniques. The aim of this study was to compare dosimetric parameters and toxicity rates at 2 years between both procedures in a matched-paired population.

Material and methods

Patients were considered for BT according to European guidelines. Among 548 patients treated at our institution, 105 patients in the loose seeds cohort were individually matched to 105 patients in the IBCLS group according to age, prostate volume, pre-operative international prostate symptom score (IPSS), clinical stage, and Gleason score. Erectile function was scored using the five-item international index of erectile function (IIEF-5) score. A multivariable linear mixed-effects model was applied to examine the association between total and individual scores (repeated measures) and covariates.

Results

Overall, 61 (29%) patients presented with a favorable intermediate-risk prostate cancer. There were no significant changes in IPSS over time (p = 0.57). During follow-up, the IIEF-5 was similar in the two groups, except at one month, where it was lower in the IBCLS group (10.9 vs. 6.9, p = 0.029). Also, there was no difference in grade ≥ 2 rectal toxicity. At 1 month, D_90Gy, V_150%, and V_100% were higher in the LS group compared to the IBCLS group.

Conclusions

Low-dose-rate prostate brachytherapy using IBCLS is a safe technique, with comparable toxicity profiles at 2 years compared to LS brachytherapy.