Comparative Study of Different β-Radiation Doses for Preventing Pterygium Recurrence

High-Dose-Rate Yttrium-90 (90Y) Episcleral Plaque Brachytherapy for Iris and Iridociliary Melanoma

Purpose

To describe a pilot study on the use of single-session, high-dose-rate, Food and Drug Administration-cleared, yttrium-90 (Y90) plaque brachytherapy for iris and iridociliary melanoma.

Design

A single-center, clinical case series.

Participants

Six consecutive patients were included in this study. Each was diagnosed with an iris or iridociliary melanoma based on clinical examination with or without biopsy.

Methods

Each tumor was staged according to the American Joint Committee on Cancer criteria and received Y90 eye plaque brachytherapy. The main variables were tumor size, patient age, sex, and method of diagnosis (clinical or biopsy). Surgical techniques, treatment durations, and ocular side effects were recorded. Local control was defined as a lack of tumor growth or regression determined by clinical examinations, including slit-lamp and gonio photography, as well as high-frequency ultrasound measurements. Toxicity parameters included acute and short-term corneal/scleral change, anterior segment inflammation, and cataract progression.

Main Outcome Measures

Local and systemic cancer control, tumor regression, visual acuity, as well as radiation-related normal tissue toxicity.

Results

High-dose-rate Y90 plaque brachytherapy was used to treat small (American Joint Committee on Cancer cT1) category melanomas. Single-surgery high-dose-rate irradiations were performed under anesthesia. Because of short treatment durations, high-dose-rate Y90 did not require the additional procedures used for low-dose-rate plaque (e.g., sutures, amniotic membrane epicorneal buffering, Gunderson flaps, and second surgeries for plaque removal). Only conjunctival recession was used to avoid normal tissue irradiation. High-dose-rate Y90 treatment durations averaged 8.8 minutes (median, 7.9; range, 5.8-12.9). High-dose-rate Y90 brachytherapy was associated with no periorbital, corneal (Descemet folds), or conjunctival edema. There was no acute or short-term anterior uveitis, secondary cataract, scleropathy, radiation retinopathy, maculopathy, or optic neuropathy. The follow-up was a mean of 16.0 (range 12-24) months. Evidence of local control included a lack of expansion of tumor borders (n = 6, 100%), darkening with or without atrophy of the tumor surface (n = 5/6, 83%), and a mean 24.5% reduction in ultrasonographically measured tumor thickness. There were no cases of metastatic disease.

Conclusions

High-dose-rate Y90 brachytherapy allowed for single-surgery, minimally invasive, outpatient irradiation of iris and iridociliary melanomas.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

First clinical implementation of Yttrium-90 Disc Brachytherapy after FDA clearance

PURPOSE

Herein, we study if high-dose-rate (HDR) yttrium-90 (⁹⁰Y) brachytherapy could be utilized by medical physicists, radiation oncologists, and ophthalmic surgeons.

METHODS AND MATERIALS

Yttrium-90 (⁹⁰Y) beta-emitting brachytherapy sources received United States Food and Drug Administration clearance for episcleral treatment of ocular tumors and benign growths. Dose calibration traceable to the National Institute of Standards and Technology as well as treatment planning and target delineation methods were established. Single-use systems included a ⁹⁰Y-disc affixed within specialized, multifunction, handheld applicator. Low-dose-rate to high-dose-rate prescription conversions and depth-dose determinations were performed. Radiation safety was evaluated based on live exposure rates during assembly and surgeries. Clinical data for radiation safety, treatment tolerability, and local control was collected.

RESULTS

Practice parameters for the medical physicist, radiation oncologist, and ophthalmic surgeon were defined. Device sterilizations, calibrations, assemblies, surgical methods, and disposals were reproducible and effective. Treated tumors included iris melanoma, iridociliary melanoma, choroidal melanoma, and a locally invasive squamous carcinoma. Mean calculated ⁹⁰Y disc activity was 14.33 mCi (range 8.8-16.6), prescription dose 27.8 Gy (range 22-30), delivered to depth of 2.3 mm (range 1.6-2.6), at treatment durations of 420 s (7.0 min, range 219 s-773 s). Both insertion and removal were performed during one surgical session. After surgery, each disc-applicator- system was contained for decay in storage. Treatments were well-tolerated.

CONCLUSIONS

HDR ⁹⁰Y episcleral brachytherapy devices were created, implementation methods developed, and treatments performed on 6 patients. Treatments were single-surgery, rapid, and well-tolerated with short-term follow up.

Evaluating the Efficacy and Safety of Different Pterygium Surgeries: A Review of the Literature

The search for the "gold standard" in the surgical treatment of pterygium has been ongoing for over two decades. Despite the development of various surgical techniques, recurrence rates range from 6.7% to 88% depending on the method used. This review discusses the latest and most commonly used methods for the surgical removal of pterygium, primarily focusing on efficacy and safety. Moreover, this review includes articles that either evaluated or compared surgical methods and clinical trials for primary and recurrent pterygium. Limited data are available on combined methods as well as on the efficacy of adjuvant treatment. The use of adjuvant intraoperative mitomycin C (MMC) and conjunctival autografting (CAU) are the two most highly recommended options, as they have the lowest rates of postoperative recurrence.

Recurrent pterygium: A review

Purpose:

To summarize the recent evidence regarding different aspects of pterygium recurrence.

Methods:

Human-based studies from PubMed, Scopus, and Google Scholar were identified using the following keywords: conjunctival disease, pterygium, recurrent pterygium, pterygium recurrence, pterygium management/surgery, conjunctival autograft (CAU), amniotic membrane graft/transplant, and adjuvant therapy (January 2009 to February 2021). We reviewed risk factors associated with the recurrence of pterygium, timing of recurrence, medical treatments to prevent from recurrence, and nonsurgical and surgical alternatives for management of recurrence.

Results:

Dry eye disease, black race, and young age are considered definite risk factors for recurrence. However, fleshy appearance of the pterygium and preoperative size remain controversial. Surgical techniques such as excessive suturing, insufficient conjunctival graft size, thick conjunctival graft with remained Tenon tissue, and postoperative graft retraction are considered possible risk factors for recurrence. Using fibrin glue instead of sutures can further reduce recurrence rates. Although recurrence could occur even after many years, most recurrences happen in the first 3–6 months after surgery. Multiple kinds of adjuvant medications are used before, during, or after the operation including mitomycin C (MMC), 5-fluorouracil (5-FU), corticosteroids, and anti-vascular endothelial growth factors (anti-VEGFs). Multiple weekly subconjunctival 5-FU injections are shown to be safe and effective in halting the progression of recurrent pterygium. Although topical bevacizumab is found to inhibit the growth of impending recurrent pterygium, the effect is mostly temporary. CAU is superior to amniotic membrane transplantation in the treatment for recurrent pterygia.

Conclusions:

There is yet to be a panacea in treating recurrent pterygium. Currently, there is not a globally accepted recommendation for treating recurrent pterygium with anti-VEGFs or 5-FU as a nonsurgical treatment. We strongly recommend using MMC as an adjunct to surgery in recurrent cases, with consideration of its specific complications. CAU is the most effective surgical treatment for recurrent pterygium, and other new surgical therapies need further investigation.

Recurrence Rate and Clinical Outcome of Amniotic Membrane Transplantation Combined with Mitomycin C in Pterygium Surgery: Two-Year Follow-Up

Objective:

To evaluate the recurrence rate and outcome of pterygium surgery with amniotic membrane transplantation (AMT) and intraoperative mitomycin C (MMC).

Methods:

This prospective clinical study included patients with pterygium who were candidates for pterygium excision. After the surgical excision, intraoperative local MMC were applied in the standard protocol followed by AMT. The outcome measures were recurrence and the size change of lesion. Kaplan-Meier estimation and regression analyses were performed.

Findings:

Fifty five eyes of 55 consecutive patients including 30 male (54.5%) and 25 female (45.5%) with mean age of 47.12 ± 15.95 years were operated. The mean follow-up period was 15.21 ± 2.67 months. The overall recurrence rate was 34.5% (19/55 cases). The estimated recurrence time for larger size of pterygium before surgery was short and marginally significant (17.14 ± 0.58 month in size of ≤3.0 mm versus. 18.56 ± 0.60 month in size of <3 mm; P= 0.06). A statistically significant association was found in reduced model among the size change of the pterygium and standardized coefficient was −0.012 (P = 0.044) and −0.743 (P < 0.001) for age and size of lesion before surgery, respectively.

Conclusion:

Our findings suggest that increasing age and pterygial tissue are the risk factors for recurrence and pterygium has a substantial recurrence rate even after AMT combined with MMC.

Radiation Therapy for Benign Disease: Keloids, Macular Degeneration, Orbital Pseudotumor, Pterygium, Peyronie Disease, Trigeminal Neuralgia

Although the use of ionizing radiation on malignant conditions has been well established, its application on benign conditions has not been fully accepted and has been inadequately recognized by health care providers outside of radiation therapy. Most frequently, radiation therapy in these benign conditions is used along with other treatment modalities, such as surgery, when the condition causes significant disability or could even lead to death. Radiation therapy can be helpful for inflammatory/proliferative disorders. This article discusses the present use of radiation therapy for some of the most common benign conditions.

Risk factors for pterygium recurrence after limbal-conjunctival autografting: a retrospective, single-centre investigation

PURPOSE

To determine the risk factors related to recurrence of pterygium after pterygium excision with limbal-conjunctival autograft.

STUDY DESIGN

Retrospective, observational case series.

METHODS

The current study included 310 patients who underwent surgical removal of pterygium using limbal-conjunctival autografting. All surgery was performed by the same surgeon at a single Hospital from 2006 to 2011. Preoperative and postoperative patient data were collected. The patients were summoned to follow-up examinations. Procedures with at least 12 months of follow-up were included in the final analysis. Potential risk factors for pterygium recurrence were determined by Cox proportional-hazard linear analysis and recurrence-free survival time was evaluated using Kaplan-Meier method.

RESULTS

The overall recurrence rate was 5.2% during an average follow-up time of 20.1±8.6 months (range, 12-37 months). According to Kaplan-Meier evaluation, the estimated time to recurrence was 34.2 ± 0.5 months (95% confidence interval 33.3-35.0 months) for the whole population. Multivariate analysis showed that age < 45 years old (RR = 3.582, 95% CI 1.984-13.044, P = 0.047), recurrent type of pterygia (RR = 4.856, 95% CI 1.794-13.142, P = 0.002), and vertical size of pterygium > 6.7 mm (RR = 2.529, 95% CI 1.053-6.075, P = 0.038) were significantly associated with increased risk of recurrence.

CONCLUSION

Our findings suggest that young age, recurrent type of pterygia, and larger pterygial tissue are risk factors for pterygium recurrence after surgical excision. Hence, early excision of pterygium is recommended to decrease the recurrence rate.

Does topical bevacizumab prevent postoperative recurrence after pterygium surgery with conjunctival autografting?

AIM

To assess the effect of topical bevacizumab use on postoperative pterygium recurrence in eyes who underwent pterygium excision with limbal-conjunctival autograft transplantation (LCAT).

METHODS

Eighty-eight eyes of 88 patients with primary pterygium were included. Pterygia were graded preoperatively from type 1 to type 3 (type 1 atrophic, type 3 inflamed) according to the inflammatory status. The eyes were preoperatively randomized to receive topical steroid and antibiotic treatment (group 1, 46 eyes) and additional topical bevacizumab (5 mg/mL; group 2, 42 eyes) in the postoperative period. All eyes underwent pterygium excision and LCAT. Medications were tapered and discontinued at one month. Postoperative complications and recurrence rates were recorded.

RESULTS

The mean follow-up duration was 29.3±4.2mo (24-52mo) and 28.5±3.4 (24-48mo) in group 1 and 2, respectively (P>0.05). There were no statistically significant differences regarding the age or gender between groups (P>0.05). Also, the difference between groups with respect to pterygium type was not significant. During the follow-up period, recurrence developed in 2 eyes (4.3%) in group 1, whereas in one eye (2.4%) in group 2. No statistically significant difference between groups was found in recurrence rates (P>0.05). No re-operation for recurrence was necessary during the follow-up period in both groups.

CONCLUSION

Topical bevacizumab seems to have no additonal effect on pterygium recurrence after LCAT.

The role of heredity in pterygium development

Several risk factors, which include heredity, ultra-violet (UV) light and chronic inflammation, contribute to pterygium development. However, there is no report integrating these factors in the pathogenesis of pterygium. The aim of this review is to describe the connection between heredity, UV, and inflammation in pterygium development. Existing reports indicate that sunlight exposure is the main factor in pterygium occurrence by inducing growth factor production or chronic inflammation or DNA damage. Heredity may be a factor. Our studies on factors in pterygium occurrence and recurrence identify that heredity is crucial for pterygium to develop, and that sunlight is only a trigger, and that chronic inflammation promotes pterygium enlargement. We propose that genetic factors may interfere with the control of fibrovascular proliferation while UV light or (sunlight) most likely only triggers pterygium development by inducing growth factors which promote vibrant fibrovascular proliferation in predisposed individuals. It also just triggers inflammation and collagenolysis, which may be promoters of the enlargement of the fibrovascular mass. Pterygium probably occurs in the presence of exuberant collagen production and profuse neovascularisation.

Young patient's age determines pterygium recurrence after surgery

BACKGROUND

It is not clear whether demographic or pterygium characteristics or limbal stem cell deficiency determine pterygium recurrence after surgery.

PURPOSE

To determine whether the demographic, pterygium characteristics, or limbal stem cell deficiency determine pterygium recurrence after excision.

METHODS

Of 190 patients operated and followed-up for 6 months, 101 and 89 underwent free conjunctival autotransplant (CAT) or limbal conjunctival autotransplant (LCAT) respectively. The age, gender, occupation, grade of pterygium extent and degree of fleshiness, and laterality were compared between recurrent and no recurrent pterygia. Multivariate analysis was performed to determine the predictors of pterygium recurrence. Recurrence rates after surgery were compared between CAT and LCAT.

RESULTS

The age range of the 190 patients was 22-65 years, mean ±SD 46.4 ±10.8 years. Pterygium recurred in 52 (27.4%). Thirty-nine (75%) of 52 patients with pterygia that recurred were aged <50 years (young) vs. 72 (52%) of 138 young patients with no recurrence; odds ratio (OR) = 1.54; 95% confidence interval (95% CI) = 0.70-3.36; p = 0.28. Thirty-one (60%) of 52 participants with post-surgical recurrent pterygia had large pre-operative pterygium (grade ≥3) vs. 130 (94%) of 138 patients with large pterygia that did not recur; OR = 0.11; 95% CI = 0.04-0.28; p <0.001. Of 101 patients undergoing CAT, 29 (28.7%) experienced recurrence vs. 23 (25.8%) of 89 undergoing LCAT; p = 0.66.

CONCLUSIONS

Young age seems to be associated with pterygium recurrence after excision followed by conjunctival graft. Large pterygia were protective.