Superficial Radiotherapy Research Articles

Cutting-Edge Technology Without Cutting: Treating Skin Cancer in This Era-A Case Series.

Traditional treatment methods for non-melanoma skin cancer (NMSC) include surgical excision with histological evaluation, yet advancements such as reflectance confocal microscopy (RCM) and superficial radiation therapy (SRT) offer non-invasive management alternatives. This study aims to evaluate the use of RCM for the evaluation of treatment outcomes after SRT in managing localized NMSC. A prospective interventional case series study was conducted on patients treated for NMSC with SRT between March 2020 and December 2023. Suspected NMSC lesions were initially evaluated with a handheld dermoscope and then imaged at multiple depths using a VivaScope 1500 RCM. Two dermatologists trained in RCM reviewed the images. Confirmed NMSC lesions were biopsied and treated with SRT, followed by RCM imaging at six months post-treatment to assess cancer clearance, scarring, and inflammation. Of the 38 lesions (composed of SCC (24) and BCC (14)) treated affecting the 29 patients, all lesions showed no residual tumor activity upon conducting follow-up RCM (100% clearance). Scarring and mild erythema were noted clinically. Six lesions demonstrated moderate to severe inflammation at a 6-month follow-up. This study demonstrates successful non-invasive management of localized NMSC using RCM and SRT. RCM was able to non-invasively demonstrate complete tumor clearance achieved by SRT with minimal adverse effects. These findings support considering the use of RCM and SRT as primary diagnostic, monitoring, and treatment options for NMSC without the need for biopsies, especially for elderly patients or those unsuitable for surgery due to medical conditions.

Image-Guided Superficial Radiation Therapy for Basal and Squamous Cell Carcinomas Produces Excellent Freedom from Recurrence Independent of Risk Factors

Background/Objectives: Basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) are non-melanoma skin cancers (NMSCs) and the most prevalent cancers in the United States. Image-guided superficial radiotherapy (IGSRT) is a relatively new treatment option that uses high-resolution dermal ultrasound integrated with superficial radiotherapy to improve tumor visualization. IGSRT is a clinically equivalent non-surgical alternative to Mohs micrographic surgery at 2 years of follow-up in early-stage NMSC, but larger cohort studies with longer follow-up periods that allow for analysis of patient outcomes by demographic and disease characteristics are needed. Methods: This large, retrospective cohort study was conducted to determine the effect of risk factors (tumor location, tumor stage, and sex) on 2-, 4-, and 6-year freedom from recurrence rates in 19,988 NMSC lesions treated with IGSRT, including lesions with complete treatment courses. Results: Overall freedom from recurrence rates were 99.68% at 2 years, 99.54% at 4 years, and 99.54% at 6 years; rates did not differ significantly by tumor location (head/neck versus other locations, p = 0.9) or sex (male versus female, p = 0.4). In contrast, there was a significant difference in freedom from recurrence rates when analyzed by tumor stage (p = 0.004). Conclusions: There was no significant effect of tumor location or sex on freedom from recurrence in IGSRT-treated NMSC. Although there was a significant difference according to tumor stage, freedom from recurrence rates exceeded 99% at all stages.

Freedom from Recurrence across Age in Non-Melanoma Skin Cancer Treated with Image-Guided Superficial Radiation Therapy.

Non-melanoma skin cancers (NMSCs) are a significant cause of morbidity and mortality; their incidence is increasing most in older patients. NMSCs have traditionally been treated with surgical excision, curettage, Mohs micrographic surgery (MMS), and superficial radiotherapy (SRT). Image-guided SRT (IGSRT) is a treatment option for poor surgical candidates or patients with low- or high-risk, early-stage NMSC who prefer to avoid surgery. This large retrospective cohort study compared 2-, 4-, and 6-year freedom from recurrence in biopsy-proven NMSC lesions treated with IGSRT (n = 20,069 lesions) between patients aged < 65 years (n = 3158 lesions) and ≥65 years (n = 16,911 lesions). Overall freedom from recurrence rates were 99.68% at 2 years, 99.57% at 4 years, and 99.57% at 6 years. Rates did not differ significantly by age (p = 0.8) nor by sex among the two age groups (p > 0.9). There was a significant difference in recurrence among older patients when analyzed by stage (p = 0.032), but no difference by stage in younger patients (p = 0.7). For early-stage NMSCs, IGSRT is a clinically equivalent alternative to MMS and statistically significant in superiority to non-image-guided SRT. This study demonstrates that there is no significant effect of age on 2-, 4-, or 6-year freedom from recurrence in patients with IGSRT-treated NMSC.

Understanding the Importance of Daily Imaging in the Treatment of Non-Melanoma Skin Cancer with Image-Guided Superficial Radiation Therapy

Image-guided superficial radiation therapy (IGSRT) combines superficial radiation therapy (SRT) with full dermal visualization (FDV) via high-resolution dermal ultrasound (HRDUS) for the treatment of non-melanoma skin cancer (NMSC). The gold standard for IGSRT delivery includes a comprehensive cancer care model with support for dermatologists from a multidisciplinary team. When delivered in this model, IGSRT can achieve cure rates of 99% for treatment of NMSC. This paper focuses on the benefits of HRDUS used in conjunction with SRT for NMSC. Medical records from 7 dermatology clinics of 883 patients with 1507 cases of NMSC treated with IGSRT between 2017 and 2018 were retrospectively reviewed. In total, 92% of the NMSC lesions showed daily depth fluctuations, 60.32% of lesions did not require changes during therapy, and nearly 40% of lesions required at least one compensatory change during therapy. In total, 83% of NMSC lesions were labeled as high risk based on the 2024 NCCN guidelines. Increasing and decreasing tumor depth measurements during IGSRT inform dermatologists when adaptive changes in energy (kV), TDF, and dose will result in more efficacy and less toxicity, respectively.

Effectiveness of postoperative superficial radiotherapy following the keloid-cross-flap surgery for auricular keloid: A prospective cohort study

Background and purposeRetaining partial keloid skin to make cross flaps (keloid-cross-flap surgery) is a modification of the core excision. This study aimed to compare the effectiveness of superficial radiotherapy versus compression therapy after keloid-cross-flap surgery. Materials and methodsIn this prospective cohort study, auricular keloid patients were consecutively screened from January 2019 to December 2021. They underwent keloid-cross-flap surgery and then enter either the superficial radiotherapy or the compression treatment group. The primary outcome was the one-year keloid recurrence rate. Secondary outcomes included: non-completion rate of adjuvant treatment; Patient and Observer Scar Assessment Scale (POSAS) scores and auricular aesthetics scores, evaluated by a four-point Likert scale (1 = poor to 4 = excellent) of non-recurring patients. Propensity score matching (PSM) was used to eliminate potential confounding factors. Results123 patients were included in the superficial radiotherapy group and 128 in the compression treatment group. Non-completion rate was significantly higher in the compression treatment group (17.97 %), while the loss rate was comparable between the two groups. Overall, 13 patients (13.54 %) relapsed in superficial radiotherapy group, while 22 patients (25.58 %) in compression group (p < 0.05). After PSM, 59 patients in each group were analyzed, and the recurrence rate was lower in the superficial radiotherapy group (13.56 %). Of relapse-free patients, no significant difference was found in PSAS scores, OSAS scores or aesthetic scores between the two groups. ConclusionKeloid-cross-flap surgery could provide favorable morphologic repair of the auricular keloid, and postoperative superficial radiotherapy shows higher compliance and lower recurrence rate comparing to compression treatment.

Post-Excision Soft X-Ray Radiotherapy for Keloids: Experience in a Tertiary Referral Center

Introduction: Keloid is an abnormal proliferation of scar tissue that grows beyond the original margins of the injury. Even after complete resection, recurrences are common and pose a poorly understood challenge in dermatology. There is lack of large prospective clinical trials; thus, treatment recommendations are based on retrospective analyses and small cohort studies. Superficial radiotherapy is recommended in recurrent keloids; however, the successful treatment rates vary greatly. The aim of this study was to evaluate the keloid recurrence rate after post-excision soft X-ray radiotherapy and the associated factors. Methods: We reviewed retrospective data of all patients, treated with adjuvant post-excision soft X-ray radiotherapy with 12 Gy in 6 sessions at the tertiary referral center, Department of Dermatology, University Hospital Zurich, Switzerland, between 2005 and 2018. We analyzed individual keloids as separate cases. Successful treatment was defined as no sign of recurrence within 2 years. Results: Of the 200 identified patients, 90 met the inclusion criteria and were included in the final analysis. In 90 patients, 104 cases of treated keloids were analyzed. Keloids were mainly located on the trunk (49%) and were mostly caused by previous surgery (52.2%). 50% of the keloids did not relapse within 2 years after therapy. A significant factor leading to recurrence was the presence of previous therapy, with prior topical therapies, such as steroid injections or 5-fluorouracil, leading to most relapses. 69.2% of keloid cases who relapsed were pretreated. Soft X-ray radiotherapy was well tolerated, with posttreatment hyperpigmentation noted in 34% of patients, particularly in patients with non-Caucasian origin (61.3%). Conclusion: Treatment of refractory keloids is difficult. Post-excision radiotherapy is an established adjuvant treatment option; nevertheless, recurrence rates are high, especially in pretreated keloids. Prospective studies determining the exact dosage and fraction of post-excisional radiotherapy are needed to determine the optimal radiation parameters.

Superficial radiation therapy in dermatology: A historical perspective

AbstractBackgroundNonmelanoma skin cancers (NMSCs), such as basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), are the most commonly diagnosed type of cancer in the United States, and the incidence of NMSC is increasing. Though surgical excision and Mohs micrographic surgery remain definitive treatments for NMSC, the majority of affected patients are advanced in age and may have relative contraindications to surgery or preferences against it. As such, there is growing value in exploring less‐invasive alternative techniques, such as superficial radiation therapy (SRT). Historically, in the decades following its inception just over a century ago, the field of SRT experienced a boom of innovations that provided the basis for treatment modalities used by dermatologists today.AimsThis paper outlines the history and evolution of SRT in dermatology and discusses SRT's modern role as an alternative to surgical management of NMSC in select patients.ConclusionAlthough a combination of aging equipment and shifts in interest toward surgical methods diminished the prominence of radiation therapy (RT) in the late 20th century, newer iterations of SRT technology have drawn renewed interest as a nonsurgical extremely effective treatment for NMSC. A brief comparison of key clinical and practical factors indicates that SRT is the optimal choice of RT technique for the definitive management of select NMSCs in patients.

Successful treatment of Giant keloid on the right toes using trepanation combined with superficial radiotherapy (SRT-100): a case report with literature review.

In dermatology, a keloid is one of the most common skin morphological abnormalities caused by excessive proliferation of fibroblasts. Keloids that are large or occur near important joint sites often cause varying degrees of physiological dysfunction in patients, therefore requiring medical treatment. A boy with congenital syndactyly developed huge keloids at the surgical site after undergoing surgical correction treatment. After treatment using trepanation combined with superficial radiotherapy (SRT-100) in our hospital, most of the boy's keloids shrank and flattened. The affected foot returned to its normal appearance, and the boy could wear shoes normally. The boy did not complain of pain, numbness, or any other distinctive discomfort after completing the treatment. This suggested that the combination of trepanation and SRT-100 may be one of the options for treating hypertrophic keloids that cannot be treated by surgical excision.

Operational Radiation Safety Considerations During Equine Superficial Radiation Treatment Using Portable X-Ray Devices

Abstract Veterinary personnel exposure due to scattered x rays, when present during superficial radiation treatment (SRT), was evaluated. Veterinary personnel presence is needed during SRT to minimize the degree of required aesthesia to horses. Animal treatment was simulated, and exposure rates determined for 50, 70, and 100 kV x rays using eight different SRT applicators. Exposure rates at the surface of a solid water phantom (SWP) phantom ranged from 3.9 mR h−1 to 396 mR h−1 for 50 kV, from 41 mR h−1 to 2,880 mR h−1 for 70 kV, and from 235 mR h−1 to 7,500 mR h−1, for 100 kV, respectively. A horse phantom was used to mimic SRT equine ocular treatment creating a spatial exposure field where the directional scatter was measured at 1 m. The minimum distance away from the source to reach &lt; 2 mR h−1 varied with angular position and energy and was lowest for all energies directly behind the x-ray tube. The closest distance before exceeding 2 mR h−1 at 50 kVp was determined to 1.96 m. A worker could stand 1 m behind the x-ray tube at 50 kVp with 0.25 mm lead for 15,106 hours. Typical SRT treatment times for horse eyelid squamous cell carcinoma are less than 5 minutes, and radiation doses to practitioners are expected to be well below local administrative ALARA limits.

Definitive superficial radiotherapy for challenging skin cancers – a case series of experiences and learnings

Definitive radiotherapy (RT) for cancer treatment offers tissue conservation. Superficial radiotherapy (SXRT) is an excellent modality for treating selected skin cancers. Through this case series, we aim to assist clinicians new to SXRT to deliver high quality care. We outline our experience in treating cancers of the lips, lower legs and ears, and discuss important planning and patient management techniques such as appropriate shielding, tumour radiation sensitivity, adequate nutrition, surveillance of regional lymph nodes, acute toxicities and patient follow-up. We highlight our experience with dose titration in response to the acute effects of RT on the cancer, and we also consider chyle leaks on the lower legs and the use of adaptive split course radiotherapy (ASCRT). Finally, we discuss the need for regular patient reviews as SXRT may not remain the most appropriate treatment modality if the lesion changes during the therapeutic course.

Image Guidance Improves Freedom From Recurrence Rate After Superficial Radiation Therapy for Nonmelanoma Skin Cancer

Image Guidance Improves Freedom From Recurrence Rate After Superficial Radiation Therapy for Nonmelanoma Skin Cancer

Superficial radiotherapy (SRT-100) for refractory plantar warts: An alternative noninvasive treatment strategy.

Verrucas that occur on the soles of the feet are called plantar warts, most of which can recur repeatedly and are difficult to eradicate. Hypertrophic and refractory plantar warts are often accompanied by pain and discomfort, which cause many inconveniences in patients' daily lives. This study aimed to analyze the therapeutic effect of superficial radiotherapy (SRT-100) on refractory plantar warts and further create favorable conditions for the subsequent treatment of this disease with a high recurrence rate. A retrospective analysis was conducted for refractory plantar warts treated with superficial radiotherapy in our outpatient department from January to June 2023. A total of 30 patients were included in our study (median age, 33 years). The female-to-male ratio was 1:3.29. Two to six months after radiotherapy, all of the warts subsided in 23 (76.67%) patients, most of the warts subsided in 4 (13.33%) patients, 3 (10%) patients did not respond to treatment, and 7 (23.33%) patients had recurrent or new warts after their warts subsided. Most patients with refractory plantar warts improved after superficial radiotherapy. Our study presented that men are more susceptible to plantar warts than women, and young and middle-aged people are the main population affected by the disease. Superficial radiotherapy is an effective treatment for refractory plantar warts, which can quickly remove the warts in a short period. It is safe and noninvasive, with minimal adverse reactions. Some patients relapse after the lesion is clear, and superficial radiotherapy can create favorable conditions for the subsequent treatment of viral warts in clinical practice.

Dust contamination of Divertor Remote Handling System in ITER Hot Cell: A novel approach to model complex superficial radiation sources

Activated dust produced by the erosion of plasma-facing components entails a significant radiation source for ITER and, generally, for all tokamaks aiming for operation under high neutron exposure. In-Vessel remote-handling operations will mobilise the dust, which will be deposited on the remote-handling tools used, for which hands-on maintenance is expected. To ensure safe maintenance of the remote-handling equipment, a dedicated decontamination process in the Hot Cell is required. Evaluating the radiation fields produced by the contaminated equipment is central to minimising radiation exposure to personnel. In this study, we present a nuclear analysis of the Divertor Remote Handling System during its transfer and decontamination process. Past computational limitations regarding superficial sources definition and high uncertainties on the dust model have been overcome by implementing a novel methodology and following an alternative approach. Two surface-dependent dust distributions over the complex geometry surfaces were considered to evaluate the dose rates according to the different contamination levels during the process phases. A scoping analysis was performed to determine the amount of dust that would comply with project requirements in each phase of the process. Improvement margins were identified in the quantification of the amount of dust and Hot Cell layout.

Efficacy of surgical resection and ultra-reduced tension suture combined with superficial radiation in keloid treatment.

There are many available treatment options for keloid; however, single treatments are usually less effective. Therefore, more scientifically rational and effective combined treatment methods should be sought to solve the pain associated with keloids. To explore the efficacy and safety of surgical resection and ultra-reduced tension suture combined with superficial radiation as keloid treatment. Fifteen keloid patients admitted to Qingdao Eighth People's Hospital from June 2020 to January 2022 were enrolled in this retrospective analysis. All patients underwent a comprehensive treatment approach comprising surgical resection, ultra-reduced tension suture incision, and superficial radiation therapy within 24 h postoperatively. The modified Vancouver Scar Scale (mVSS) and Patient and Observer Scar Assessment Scale (POSAS) were used to evaluate the treatment effect, whereas the efficacy, adverse effects, and recurrence rate were observed according to the 12-mo follow-up after treatment. The mVSS and POSAS scores at 1 and 6 mo after combination treatment decreased compared to before treatment (P < 0.001), and the overall response rate was 93.3%. Only one case recurred, yielding a 6.7% recurrence rate. The incidence of local chromour sedimentation rate in 1-3 mo after radiotherapy was 33.3% (5 patients), all subsiding after 6-9 mo, without complications, such as delayed wound healing or dermatitis. Surgical resection, super subtraction sutures, and superficial radiotherapy are treatment methods with short courses, low recurrence rates, and good safety profiles.

Diagnosis and Treatment of Keloid: Method Summary and Effect Evaluation.

Keloid is a prevalent skin disorder characterized by the abnormal growth of keloid tissue, which usually occurs following wound healing or surgical incisions. It typically progresses through several stages: the inflammatory stage, the proliferative stage, collagen remodeling, and ultimately the formation of keloid. This review aims to summarize the diagnostic and therapeutic methods for keloid, and evaluate their effectiveness. The diagnosis of keloid is usually based on medical history and clinical manifestations such as pain, itching, erythema, and induration. Other commonly used diagnostic methods include tissue biopsy and ultrasound examination. Various treatment options for keloid exist, including physical therapy, medication, surgical treatment, and radiation therapy. Physical therapy includes pressure therapy, laser therapy, such as silicone sheets, elastic bandages, and laser irradiation. Medication treatment mainly involves the application of topical medications or intralesional injections, such as topical corticosteroids, 5-fluorouracil, and others. Radiation therapy can be administered using applicators and superficial radiation therapy, among other methods. The treatment outcomes of keloid vary from person to person and recurrence is common. Therefore, a comprehensive treatment approach may be the most effective strategy. Individualized treatment plans should consider factors such as the patient's age, gender, medical history, and the severity of the condition. In conclusion, the diagnosis and treatment of keloid require consideration of multiple factors and the implementation of individualized treatment plans. Future research should focus on identifying the molecular mechanisms underlying the occurrence and progression of keloid in order to develop more effective treatment methods.

Successful Treatment of Unilateral Hailey-Hailey Disease

Hailey-Hailey Disease is a notoriously difficult to treat genodermatosis. While several treatment modalities are available, successful treatment of recalcitrant disease is not well documented. Superficial radiotherapy, a treatment typically reserved for skin cancer, has recently been utilized to treat Hailey-Hailey disease. In this case report we present the successful treatment of Hailey-Hailey disease in a patient with an unusual unilateral multifocal presentation. Based on the results of this case report, we believe SRT has strong potential to become the standard of care for recalcitrant HHD. Though there are risks to this treatment, the overall risks are minor compared to the decades of antibiotics, recurring infections, long term scarring and loss of self-esteem that arise from chronic recalcitrant HHD.

The assessment of the clinical impact of using a single set of radiotherapy planning data for two kilovoltage therapy units.

Kilovoltage therapy units are used for superficial radiotherapy treatment delivery. Peer reviewed studies for MV linear accelerators describe tolerances to dosimetrically match multiple linear accelerators enabling patient treatment on any matched machine. There is an absence of literature on using a single planning data set for multiple kilovoltage units which have limited ability for beam adjustment. This study reviewed kilovoltage dosimetry and treatment planning scenarios to evaluate the feasibility of using ACPSEM annual QA tolerances to determine whether two units (of the same make and model) were dosimetrically matched. The dosimetric characteristics, such as measured half value layer (HVL), percentage depth dose (PDD), applicator factor and output variation with stand-off distance for each kV unit were compared to assess the agreement. Independent planning data based on the measured HVL for each beam energy from each kV unit was prepared. Monitor unit (MU) calculations were performed using both sets of planning data for approximately 200 clinical scenarios and compared with an overall agreement between units of < 2%. Additionally, a dosimetry measurement comparison was completed at each site for a subset of nine scenarios. All machine characterisation measurements were within the ACPSEM Annual QA tolerances, and dosimetric testing was within 2.5%. This work demonstrates that using a single set of planning data for two kilovoltage units is feasible, resulting in a clinical impact within published uncertainty.

IAEA/WHO postal dosimetry audit methodology for electron beams using radio photoluminescent dosimeters.

Independent dosimetry audits are an important intervention in radiotherapy for quality assurance. Electron beams, used for superficial radiotherapy treatments, must also be tested in dosimetry audits as part of a good quality assurance program to help prevent clinical errors. To establish a new service for IAEA/WHO postal dosimetry audits in electron beams using RPL dosimeters. A novel postal audit methodology employing a PMMA holder system for RPLDs was developed. The associated correction factors including holder dependence, energy dependence, dose response non-linearity, and fading were obtained and tested in a multi-center (n=12) pilot study. A measurement uncertainty budget was estimated and employed in analyzing the irradiated dosimeters. Holder and energy correction factors ranged from 1.004 to 1.010 and 1.019 to 1.059 respectively across the energy range. The non-linearity and fading correction models used for photon beams were tested in electron beams and did not significantly increase measurement uncertainty. The mean dose ratio±SD of the multi-center study was 1.001±0.011. The overall uncertainty budget was estimated as±1.42% (k=1). A methodology for IAEA/WHO postal dosimetry audits in electron beams was developed and validated in a multi-center study and is now made available to radiotherapy centers as a routine service.

Image-Guided Superficial Radiation Therapy Has Superior 2-Year Recurrence Rates to Mohs Micrographic Surgery

Non-melanoma skin cancers (NMSCs) are the most common malignancy in the USA, and incidence is rising. Mohs micrographic surgery (MMS) is a tissue-sparing surgical technique often used in NMSCs. Superficial radiation therapy (SRT) was widely used prior to the advent of MMS, but MMS has superior recurrence rates and replaced SRT as a first-line therapy. Image-guided SRT (IGSRT) was invented in 2015 and utilizes ultrasound to improve SRT precision and produces minimal side effects (99% grade 1 or 2).[1] The hypothesis is that NMSCs treated with IGSRT will have improved 2-year recurrence rates of compared to those treated with Mohs micrographic surgery. This retrospective cohort study compared the 2-year recurrence probability of early stage NMSCs (squamous and basal cell carcinomas (SCCs and BCCs)) treated by IGSRT (2,286 lesions) to data on NMSCs treated by MMS (5,391 lesions) via one sample proportion tests. IGSRT-treated NMSC data is from a database published by Yu et al.[1] The 2-year recurrence probability statistical analysis is from McClure et al.[2] Medical Subject Headings were used to search PubMed for reports of 2-year recurrence rates of NMSCs treated by MMS. Seventeen studies were screened; 14 studies were excluded for lack of 2-year time to event analysis, or irrelevant patient population (non-BCC/SCC study, advanced disease), leaving 3 studies for comparison. IGSRT-treated NMSCs have a statistically significantly improved 2-year recurrence rates compared to MMS-treated (p<0.001 for pooled data). When separated by histology, 2-year recurrence rates of all reported SCCs and BCCs treated by MMS were also inferior to those treated by IGSRT, p<0.001, p = 0.0218, respectively. In this analysis, IGSRT has superior 2-year recurrence rates. Limitations include insufficient follow-up to report on the 5-year recurrence probability and inability to adjust for confounding factors beyond histology. This data implies that IGSRT is a well-tolerated, paradigm-shifting treatment option for patients with early stage NMSCs who cannot tolerate or refuse surgery. IGSRT provides patients the choice of treatment modality that best aligns with their goals of care.

Proof-of-Concept and Characterization of Photosynthetic Bacteria as Radiation Enhancers

Molecular O2 is a potent chemical radiosensitizer. Re-sensitizing hypoxic tumor tissues with O2 can enhance the therapeutic efficacy of ionizing radiation. Photosynthetic cyanobacteria (S. elongatus) or cyanos are currently being explored for various bioengineering applications due to their ability to produce oxygen when exposed to light. Here, we explore the use of these bacteria to replenish molecular O2 content inside hypoxic tumors, which in turn will enhance the effect of radiation. To assess the feasibility of this approach, we used A549 lungs cancer cell spheroids as models, which are three-dimensional (3D) in vitro cell aggregates that mimic tumors in terms of oxygen and nutrient gradients. The cyanos were grown in 12:12h light /dark conditions in a bacterial shaker incubator (37ºC and 150 rpm). Biocompatibility of cyanos co-cultured withA549 monolayers and spheroids was estimated using the MTT assay and Calcein AM staining. The level of hypoxia content in the spheroids were measured using the Image IT green hypoxia dye. Spheroids co-cultured with cyanos were subjected to full spectrum lights for different time periods. After light incubation, different dosages of radiation (4, 6 and 12 Gy) were delivered to the spheroids using an X-ray irradiator (225 kBp, 13 mA). Post irradiation, the spheroids were harvested and analyzed based on Nuc green dye staining to estimate the dead cell population and clonogenic survival to estimate the post-therapy survival fraction. Under exposure to full spectrum LED light, cyanos increased the concentration of dissolved O2 in the medium, eventually reaching fourfold higher levels (i.e., ∼240% of dissolved O2). Addition of cyanos to mammalian cell cultures did not result in detectable toxicity for either cellular monolayers or 3D spheroids. Cell viability was 100% even at the highest tested concentration of 1 × 107 number of cyanos cultured with 10,000 A549 cells. This confirmed the biocompatibility of the cyanos in cell culture environment. Post irradiation, as depicted from the Nuc green dye staining, was twofold higher (p<0.01) in spheroids co-cultured with cyanos and exposed to light. Surprisingly, in the clonogenic assay, this group of spheroids exhibited a higher survival fraction compared to the control group. This unexpected outcome warrants further investigation of the potentially radioprotecting effect of cyanos. Altogether, this supports the potential therapeutic efficacy of the cyanos in hypoxic tumors. Cyanos in the presence of light are effective in enhancing radiation-induced cell death. While clinical translation is still far down the road, such a method could be employed in the context of brachytherapy or superficial radiotherapy to overcome tumor hypoxia.