Prospective study of exclusive strontium-/yttrium-90 beta-irradiation of primary and recurrent pterygia with no prior surgical excision. Clinical outcome of long-term follow-up

Long-Term Safety and Outcomes of β-radiation for Trabeculectomy

PRCIS

β-radiation is a neglected antiscarring therapy with past concerns for safety. This report found it safe and efficacious when used as an adjuvant to trabeculectomy surgery in 101 people (135 eyes) over 20 years.

PURPOSE

β-radiation has been used as an adjunct to prevent scarring in trabeculectomy surgery for many decades. Safety concerns were raised with the use of high doses on the bare sclera. Moorfields Eye Hospital has a large cohort of patients who have received β-radiation therapy. We report a review of the long-term safety and efficacy.

METHODS

Cases undertaken between August 1992 and August 1996 were reviewed. Those with records available for postoperative review of more than 5 years were included. Failure (reintervention/>21 mm Hg on 2 successive occasions) and any complication previously reported in association with β-radiation were the primary outcomes.

RESULTS

In total, 292 operations using β-radiation were recorded and 101 people (135 eyes) with trabeculectomy surgery and postoperative follow-up for over 4.5 years were included. The median follow-up period was 22.5 years. At the final follow-up, 48 (48%) single eyes per person had failed and 20/51 (51%) eyes with primary open angle glaucoma had cataract surgery. Other complications were rare and associated with copathology.

CONCLUSION

In glaucoma patients at risk of scarring and failure after trabeculectomy, as an antiscarring adjuvant, a 750 cGY dose of β-radiation was found to be safe and efficacious in the long term.

Changes of Corneal Biomechanical Properties upon Exclusive Ytt-/Sr-90 Irradiation of Pterygium

BACKGROUND

It is known that pterygia above a certain size cause astigmatism and other aberrations of the human cornea and thus impair the quality of vision. Exclusive Sr-/Ytt-90 beta irradiation is a highly effective treatment for primary pterygia. The aim of this retrospective study is to determine the extent to which higher order corneal aberrations are affected by this treatment.

METHODS

Evaluation of corneal topographies and wavefront aberration data of 20 primary pterygia patients generated before and at different points in time in the first year after irradiation. Additionally, the size of the pterygium was measured.

RESULTS

The study showed a significant increase in coma and triple leaf aberrations in pterygia with a horizontal length of 2 mm and more. It was also found that a pterygium size greater than 2 mm significantly induces astigmatism. Both phenomena reduce visual quality. In none of the patients could a pterygium recurrence be detected after irradiation.

CONCLUSIONS

If the pterygium size is less than 2 mm, early exclusive Sr/Ytt-90 beta irradiation can be recommended. If the size is more than 2 mm, a pterygium excision 6 months after beta irradiation can be discussed.

Long-Term Results of P.E.R.F.E.C.T. for PTERYGIUM

PURPOSE

To identify the recurrence rate, complication rate, cosmetic results, and patient satisfaction after P.E.R.F.E.C.T. for PTERYGIUM more than 10 years after surgery.

METHODS

This is a prospective cohort study with 312 patients (351 surgeries). All patients underwent pterygium removal using P.E.R.F.E.C.T. for PTERYGIUM in 1 eye or both eyes by the author. The main parameters studied were recurrence rate, complication rate, esthetic outcomes, and patient satisfaction.

RESULTS

Two hundred twenty-nine patients (77% of surviving cohort group) were able to be followed up with 16 patients deceased. The basic biographical data of the group followed up and those lost to follow-up were not different. The follow-up period was 153 ± 20 months. Twenty-five percent of the surgeries were for recurrent pterygia. The recurrence rate was zero, and there were no serious complications. Ninety-four percent of patients were graded as having normal or excellent cosmetic appearance by the surgeon, and 95% of the patients graded the appearance of their eye as greater than 8 of 10. Ninety-four percent of the patients gave more than 8 of 10 as their satisfaction with the service and surgery.

CONCLUSIONS

P.E.R.F.E.C.T. for PTERYGIUM provides long-term and stable results for primary and recurrent pterygium patients with a zero recurrence rate and excellent cosmetic appearance of the eye and no serious complications. P.E.R.F.E.C.T. for PTERYGIUM should be considered as the standard by which other pterygium surgeries should be compared. Cosmetic outcomes after pterygium surgeries are now a more sensitive measure of success than recurrence rate alone.

Biomechanical Modeling of Pterygium Radiation Surgery: A Retrospective Case Study

Pterygium is a vascularized, invasive transformation on the anterior corneal surface that can be treated by Strontium-/Yttrium90 beta irradiation. Finite element modeling was used to analyze the biomechanical effects governing the treatment, and to help understand clinically observed changes in corneal astigmatism. Results suggested that irradiation-induced pulling forces on the anterior corneal surface can cause astigmatism, as well as central corneal flattening. Finite element modeling of corneal biomechanics closely predicted the postoperative corneal surface (astigmatism error −0.01D; central curvature error −0.16D), and can help in understanding beta irradiation treatment. Numerical simulations have the potential to preoperatively predict corneal shape and function changes, and help to improve corneal treatments.

Portfolio of prospective clinical trials including brachytherapy: an analysis of the ClinicalTrials.gov database

Background

To evaluate the current status of prospective interventional clinical trials that includes brachytherapy (BT) procedures.

Methods

The records of 175,538 (100 %) clinical trials registered at ClinicalTrials.gov were downloaded on September 2014 and a database was established. Trials using BT as an intervention were identified for further analyses. The selected trials were manually categorized according to indication(s), BT source, applied dose rate, primary sponsor type, location, protocol initiator and funding source. We analyzed trials across 8 available trial protocol elements registered within the database.

Results

In total 245 clinical trials were identified, 147 with BT as primary investigated treatment modality and 98 that included BT as an optional treatment component or as part of the standard treatment. Academic centers were the most frequent protocol initiators in trials where BT was the primary investigational treatment modality (p < 0.01). High dose rate (HDR) BT was the most frequently investigated type of BT dose rate (46.3 %) followed by low dose rate (LDR) (42.0 %). Prostate was the most frequently investigated tumor entity in trials with BT as the primary treatment modality (40.1 %) followed by breast cancer (17.0 %). BT was rarely the primary investigated treatment modality for cervical cancer (6.8 %).

Conclusion

Most clinical trials using BT are predominantly in early phases, investigator-initiated and with low accrual numbers. Current investigational activities that include BT mainly focus on prostate and breast cancers. Important questions concerning the optimal usage of BT will not be answered in the near future.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-016-0624-8) contains supplementary material, which is available to authorized users.

Reirradiation of spinal column metastases: comparison of several treatment techniques and dosimetric validation for the use of VMAT

BACKGROUND

For reirradiation of spinal column metastases, intensity-modulated radiation therapy (IMRT) reduces the dose to the spinal cord, while allowing longer treatment times. We analyzed the potential of volumetric modulated arc therapy (VMAT) to reduce treatment time and number of monitor units (MU).

PATIENTS AND METHODS

In CT datasets of 9 patients with spinal column metastases, the planned target volume (PTV) encompassed the macroscopic tumor including the spinal cord or medullary cone, respectively. The prescribed dose for the target was 40 Gy, but median spinal cord dose was intended to be < 26 Gy. We compared a posterior (3D-PA) static field technique, a two-field wedge technique (3D-wedge) and 5-/7-beam IMRT with VMAT. Conformity index (CI), homogeneity index (HI40), dose volume histogram (DVH) parameters, treatments delivery time (T), and MU were analyzed. Dosimetry was validated with EDR2-film/ionization chambers.

RESULTS

PTV coverage was insufficient for 3D-conformal radiotherapy (3D-CRT) when spinal cord tolerance was respected. The IMRT approach provided excellent results but has the longest treatment time. VMAT produced dose distributions similar to IMRT with shorter treatment times (VMAT: mean 4:49 min; IMRT: mean 6:50 min) and fewer MU (VMAT: 785; IMRT: 860). Reduced conformity and increased homogeneity for VMAT when compared to IMRT were observed. An absolute deviation between measured and calculated dose of +0.70 ± 3.69% was recorded. γ-Index analysis showed an agreement of 91.33 ± 3.53% for the 5%/5 mm criteria.

CONCLUSION

For this paradigm, VMAT produces high quality treatment plans with homogeneity/conformity similar to static IMRT, shorter treatment times, and fewer MU. Verification measurements showed good agreement between calculation and delivered dose, leading to clinical implementation.

[The significance of radiation therapy for symptomatic vertebral hemangiomas (SVH)]

PURPOSE

To evaluate the efficacy of radiation therapy (RT) for symptomatic vertebral hemangioma (SVH).

MATERIAL AND METHODS

Based on the Registry for Rare Benign Disorders (RRBD) of the German Cooperative Group on Radiation Therapy for Benign Diseases (GCG-BD), the clinical information, treatment plans and outcome data from seven cooperating German RT institutions were analyzed retrospectively.

RESULTS

Over a period of 39 years (1969-2008), a total of 84 patients with 96 symptomatic lesions underwent RT. The predominant indication was pain in 97.6%, and, in addition, 28.6% of patients had neurological deficits. The median total dose was 34 Gy (4.5-45 Gy), and the median single dose 2.0 Gy (0.5-3.0 Gy). After a median follow-up of 68 months (6-422 months), complete symptom relief (CR) occurred in 61.9% of patients, 28.6% had partial relief, and 9.5% had no relief (NR). The overall response rate (CR + PR) was 90.5%. In 26.2% of patients, radiologic signs of remineralization were noted. After a median follow-up of 70 months (8-124 months), symptom progression occurred in eight patients (9.5%). Therefore, the long-term rate of local control was 80.9%. Multivariate statistical analysis revealed a significantly higher rate of symptom relief and local control for total doses > or = 34 Gy. Side effects > RTOG/EORTC grade 2 were not observed.

CONCLUSION

RT is a safe and effective for treatment of SVH. Total doses of at least 34 Gy are recommended to achieve optimal treatment response.