The purpose of this retrospective-prospective study is to evaluate lesions after treatment for BCC or SCC NMSC in order to gain a better understanding of the durability of the treatment, and risk of late toxicities for this patient population.

This is a retrospective-prospective study design. The study is post-market, on-label observational study for the treatment of NMSC. Patients who completed treatment at least five years from the last treatment will be identified and existing data as required by this protocol in the patient's record will be collected in addition to conducting office visits or telehealth visits (video) for long-term follow-up.

The study will include:

Identifying patients, retrospectively, who completed treatment a minimum of five years from the last treatment. The history and demographic data will be collected from up to 300 subjects previously treated with eBx for the treatment of NMSC. Patients will have an office visit or telehealth visit in order for the investigators to assess the lesion site, document absence of recurrence, treatment for recurrence (if applicable), and long-term toxicities at the time of the prospective visit.

Inclusion Criteria:

1. Previously completed treatment for non-melanoma skin cancer using Xoft eBx Electronic Brachytherapy System according to standard of care;16
2. Provides informed consent;
3. Greater than 40 years of age;
4. Pathological diagnosis confirmed to be squamous cell carcinoma, or squamous cell carcinoma-in-situ, or basal cell carcinoma prior to treatment;
5. Cancer Staging included in this study:

Stage 0: Tis, N0, M0 Stage 1: T1a, b, c, N0, M0 Stage 2: T2a, N0, M0

Exclusion Criteria:

1. Target area is adjacent to a burn scar;
2. Any prior definitive surgical resection of the cancer, prior to Radiation Treatment;
3. Known perineural invasion;
4. Actinic Keratosis;
5. Known spread to regional lymph nodes;
6. Known metastatic disease;
7. Lesion treated with Mohs surgery.

The first phase of this study will be to identify patients who completed treatment with eBx at least five years ago prior to study onset and collect history and demographic data, and eligibility data retrospectively from the patient records and on source worksheets.

No plan not sharing IPD

Subjects with eBx Treatment that completed at least 5 Year Follow-up.

Retrospective review of subject's post Xoft eBx or MMS treatment completed 5-10 years ago, data assessed during a 1-day long-term prospective clinic visit by study completion.

Select Skin toxicity adverse events according to CTCAE.