This study will observe the efficacy and toxicities of 3-dimensional printing noncoplanar template assisted CT guided radioactive iodine-125 seeds implantation in the treatment of patients with recurrent chest wall malignancies after external beam radiotherapy prospectively, and analyzes the influence of clinical and dosimetric factors on the outcomes.

Radioactive Iodine-125 seed brachytherapy is a conventional treatment in Peking University Third Hospital. Radioactive Iodine-125 seed brachytherapy is the implantation of Iodine-125 seed into tumors.The radioactive Iodine-125 seed can release low dose of irradiation persistently which kills tumors cell and causes less damage to normal tissue at the same time. This study will enroll the patients with recurrent chest wall malignancies after external beam radiotherapy (primary or metastasis) who underwent CT-guided radioactive iodine-125 seed implantation assisted by 3D-printing template from 2019 to 2021. The investigators evaluate the dose that covers 90% target volume(D90) and other parameters after the implantation. The efficacy and adverse events will be observed. Local control(LC) time and overall survival(OS) time are evaluated.

Inclusion Criteria:

• histological proven malignant tumor
• tumor located in chest wall and lesion diameter <= 10 cm
• recurrence after external beam radiotherapy
• there is no bleeding tendency
• there are no serious or uncontrolled underlying diseases (such as severe or uncontrolled hypertension, diabetes, cardiovascular and cerebrovascular diseases, and/or organ dysfunction
• there is an appropriate puncture path which is expected to achieve the treatment dose
• KPS > 70, which is expected to be able to tolerate puncture/ brachytherapy, and the expected survival time is longer than 3 months

Exclusion Criteria:

• there are skin ulceration, or with high risk of skin infection and ulceration
• liquefaction and necrosis in a large area in tumor with poor expected seeds distribution
• pregnant women, lactating women, psychiatric patients
• patients with poor compliance can not complete the treatment
• patients that researchers considered inappropriate to participate in this clinical trial

The patients with chest wall malignancies (primary or metastasis) who were treated with CT-guided radioactive iodine-125 seeds implantation assisted by 3D-printing template during 2019 to 2021 will included in the study.

De-identified individual participant data for all primary and secondary outcome measures will be made available.

Data will be available within 6 months of the study completion.

Data access requests will be reviewed by an external Independent Review Panel. Requestors will be required to sign a Data Access Agreement.