Role of brachytherapy in the management of pulmonary and mediastinal malignancies

Stereotactic Ablative Brachytherapy: Recent Advances in Optimization of Radiobiological Cancer Therapy

Brachytherapy (BT), a type of focal anti-cancer radiotherapy, delivers a highly focused radiation dose to localized tumors, sparing surrounding normal tissues. Recent technological advances have helped to increase the accuracy of BT and, thus, improve BT-based cancer treatment. Stereotactic ablative brachytherapy (SABT) was designed to improve the ablative effect of radiation, which was achieved via improved image guidance, and calculation of ablative dose, shorter treatment duration, and better organ preservation. Recently collected data characterized SABT as having the potential to cure various early-stage cancers. The method provides higher tumor control rate levels that were previously achievable only by surgical resection. Notably, SABT is suitable for application with unresectable malignancies. However, the pathological assessment of SABT irradiated tumors is limited due to difficulties in specimen acquisition. Prostate, lung, liver, and gynecological cancers are the most commonly reported SABT-treated malignancies. This study will give an overview of SABT, focusing on the advances in SABT optimization, and provide insights on the future benefits of the combined application of SABT with cancer immunotherapies.

Brachytherapy for lung cancer

Brachytherapy (BT) is a minimally invasive anticancer radiotherapeutic modality where the tumor is directly irradiated via a radioactive source that is precisely implanted in or adjacent to the tumor. BT for lung cancer may be conducted in the form of endobronchial BT and radioactive seed implantation (RSI-BT), mainly for nonsmall cell lung cancer (NSCLC). For patients with early-stage lung cancer who are not suitable for surgery or external beam radiotherapy (EBRT), BT may be used as an alternative treatment, and curative results could be achieved in certain patients with cancer confined to the trachea lumen. For patients with locally advanced/metastatic lung cancer, BT could be selectively applied alone or as a boost to EBRT, which could improve the local tumor control and patient's survival. In addition, BT is also useful as a salvage treatment in select patients with locally recurrent/residual lung cancer that failed other treatments (e.g., surgery, chemotherapy, and EBRT). However, clinical outcomes are mainly obtained from retrospective studies. Prospective studies are limited and needed. In recent years, the introduction of modern image guidance, novel radioactive seeds, BT treatment planning systems (BT-TPS), after-loading technique, and three-dimensional printing template (3D-PT) assistance, among others, have potentially improved the clinical outcomes of BT. However, a comprehensive review of BT with newly published literature was lacking. This review is to discuss BT for NSCLC based on recent literature published in PubMed.

Comparison of pre-implant treatment planning and post-implant dosimetry in I-125 spinal metastases brachytherapy

I-125 seed therapy has been developed and used for the treatment of numerous types of malignancies. It has been suggested that post-implant dosimetry deviates from pre-implant treatment planning; however, to the best of our knowledge, very few studies to date have investigated this discrepancy. In the present study, 11 patients with metastatic spinal tumors, who were treated with I-125 seed brachytherapy, were assessed. Pre- and post-implant dosimetry were compared by assessing: Tumor volume, dose distributions and dose volume histograms. The average doses delivered to 90% of the target volume (D90) in the pre-implant planning images of the spine was 119.07 Gy compared with 94.15 Gy in the post-implant dosimetry (P<0.05). The average V100 in the pre-implant planning images of the spine was 97.85% (range, 96.50–99.80%), compared with 84.46% (range, 66.40–96.70%) in the post-implant dosimetry, of the prescribed doses (P<0.05). Furthermore, both the number of needles and the Dmax of the cord differed between the two groups. Nevertheless, the mean gross tumor volume, the number of seeds, and the V150 and V200 were similar between the two groups. The results of the present study suggest that metastatic spinal tumors of the bone received a lower dose than the pre-implant planned dose coverage in I-125 seed brachytherapy.

Surgery Combined with Radiotherapy to Treat Spinal Tumors: A Review of Published Reports

Spinal tumors result in high morbidity and a high rate of lower limb paralysis. Both surgical therapy and radiation therapy (RT) are used to treat spinal tumors; however, how best to combine these two therapies to maximize the benefits and minimize the risks is still being debated. It is also difficult to decide the optimal timing, course and dose of RT, especially in pregnant women and children. The aim of this review is to assist surgeons who are dealing with spinal tumors by providing comprehensive information about advanced techniques for administering RT with greater precision and safety, and about the impact of various ways of combining surgery and RT on therapeutic outcomes. We here review published reports about treating spinal tumors with a combination of these two forms of therapy and attempt to draw appropriate conclusions concerning selection of optimal treatment protocols. Our conclusion is that postoperative radiotherapy, especially with high-precision, low-dose and multiple fractions, and brachytherapy are promising therapies to combined with surgery.

Sodium glycididazole enhances the efficacy of combined iodine-125 seed implantation and chemotherapy in patients with non small-cell lung cancer

The aim of the present study was to investigate the efficacy and safety of combined therapy with iodine-125 seed implantation and the gemcitabine plus cisplatin chemotherapeutic regimen, as well as treatment with the radiosensitizer sodium glycididazole (CMNa), in patients with non-small cell lung cancer (NSCLC). The 40 patients with NSCLC in the experimental group (19 females; mean age, 52.3±11.5 years; age range, 34-74 years) received the combined therapy and CMNa, and the 41 controls (13 females; mean age, 53.7±10.7 years; age range, 8-79 years) received the combined therapy only. The response rate in the experimental group was significantly higher than in the control group (85.5 vs. 63.4%; P=0.027), with no apparent complications. Therefore, it was concluded that such therapy may be reliable and well-tolerated for the treatment of patients with NSCLC.

Computed tomography-guided permanent brachytherapy for locoregional recurrent gastric cancer

BACKGROUND

Locoregional recurrence is the typical pattern of recurrence in gastric cancer, and cannot be removed by surgery in most of the patients. We aimed to evaluate the feasibility and efficacy of computed tomography (CT)-guided brachytherapy for patients with locoregional recurrent gastric cancer.

MATERIALS AND METHODS

We reviewed the case histories of 28 patients with locoregional recurrent gastric cancer that were selected for CT- guided brachytherapy by a multidisciplinary team. The clinical data of the patients including patient characteristics, treatment parameters, short-term effects, and survival data were collected and analyzed.

RESULTS

15-75 125I seeds were implanted into each patient to produce a minimal peripheral dose (MPD) 100-160 Gy. Median day 0 dosimetry was significant for the following: V100 (the volume treated with the prescription dose) 95.8% (90.2-120.5%) and D90 (prescription dose received by at least 90% of the volume) 105.2% (98.0-124.6%) of prescription dose. No serious complications occurred during the study. Two months after brachytherapy, complete response, partial response and progressive disease were observed in 50.0%, 28.6% and 21.4% of patients, respectively. The median survival time was 22.0 ± 5.2 months, and the 1, 2,and 3-year survival rate was 89 ± 6%, 52 ± 10% and 11 ± 7%, respectively. A univariate analysis showed that the tumor size was a significant predictor of overall survival (P = 0.034). Patients with tumors <3 cm had relatively higher complete response rate (66.7%), compared to those with tumors >3 cm (30.8%). The PTV (planning target volume) smaller than 45 cm3 was significantly correlated with achieving complete tumor eradication in the treated region (P = 0.020).

CONCLUSIONS

For selected patients with limited locoregional recurrent gastric cancer, CT-guided brachytherapy using 125I seeds implantation can provide a high local control rate, with minimal trauma.

Interstitial 125I seeds implantation to treat spinal metastatic and primary paraspinal malignancies

Spinal cord metastatic malignancies and locally invasive paraspinal carcinomas were severe pain and disabling complications. The treatment modality was unclear. We retrospectively evaluated the safety and efficacy of (125)I seed implantation for spinal metastatic and paraspinal malignancies in our center. A total of 19 patients and 22 procedures were included in this study. Eight patients received a seed implant in an operation, and 11 patients were implanted percutaneously under CT-guidance. The number of (125)I seeds implanted ranged from 6 to 100, with a median of 26. The specific activity of (125)I seeds ranged from 0.45 to 0.80 mCi per seed, with a median of 0.5 mCi. The minimal peripheral doses of (125)I seed implantation were 90-140 Gy, with median of 120 Gy. Follow-up ranged from 3 to 69 months with a median of 22 months. All patients tolerated seed implantation well. The 1, 2, 3, and 5 year local control rates were 63%, 47%, 31%, and 3%, respectively, with a median of 22 months (3-61 months). The 1, 2, 3, and 5 year survival rates were 74%, 56%, 43%, and 43%, respectively, with a median of 33 months. Ten patients (52.6%) developed distant metastases. Two (10.5%) patients showed recurrence at 13 and 39 months. Seven (36.8%) patients were still alive, 84% (16/19) of patients had either normal or improved ambulation following seed implant. No myelopathies were encountered. Our study suggests a promising local therapy for a selected population of patients with spinal cord metastatic or paraspinal carcinoma.

Limited resection for non-small cell lung cancer: observed local control with implantation of I-125 brachytherapy seeds

BACKGROUND

Limited resection for lung cancer has been associated with a relatively high incidence of local recurrence. This retrospective study evaluates the impact of implanting radioactive iodine-125 (125I) seeds along the resection margin in these patients.

METHODS

Thirty-three patients with lung cancer who were not candidates for lobectomy or pneumonectomy underwent a limited resection of 35 primary non-small cell lung cancers. 125I brachytherapy seeds were implanted along the resection margin to reduce the risk of local recurrence. Survival using the Kaplan-Meier method and sites of recurrence were documented. Follow-up ranged from 20 to 98 months (median, 51 months).

RESULTS

The 5-year survival was 47% for all patients. For patients with T1N0 tumors, it was 67%, and for patients with T2N0 tumors, it was 39%. However, the cancer-specific survivals were 77% and 53% for patients with T1N0 and T2N0 tumors, respectfully. Ten patients experienced recurrence, with two local (at the resection margin) and six regional recurrences (five mediastinum, one chest wall). Both local recurrences and one regional recurrence occurred in the 19 patients with T1N0 tumors.

CONCLUSIONS

125I seed implantation along the resected margin for compromised patients undergoing limited resection of lung cancer results in a relatively low incidence of local recurrence and may prolong survival.