Recognizing Unusual Tumors Part 2: Disruptive Technologies for Skin Cancer: Electronic Brachytherapy and Superficial Radiation

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Hayes B. Gladstone

As noted in previous sections, a wide range of treatment modalities are available for patients with basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC).  Surgical options include curettage with electrodessication, Mohs micrographic surgery, and surgical excision; and they provide high control rates and generally satisfactory cosmetic results. However, some patients are not suitable candidates for surgery and some cases of non-melanoma skin cancer (NMSC) may not be optimally treated with surgery due to the potential for disfigurement.

Radiation Therapy

Radiation therapy, including external beam and brachytherapy techniques, has been used as primary and post-surgical adjuvant therapy for NMSC and results from published studies have indicated local control ranging from 84-97% with good tolerability (Khan, 2014).

Electronic Brachytherapy

Electronic brachytherapy (EBT) is the administration of high dose rate brachytherapy without the use of a radioactive isotope and with minimal shielding requirements due to the low energies utilized with this system.  This novel approach has been demonstrated to be effective in a large series of 187 patients with 277 NMSC lesions.  At a mean follow-up of 13 months (range = 1-51 months) there were no recurrences. The most frequent acute effects were rash in 90 (44.1%), pruritus in 9 (4.4%) and hyperpigmentation in 4 (2.0%) of 204 lesions evaluated at 1 month after treatment. The most frequent late effects were hypopigmentation in 17 (10.1%) and alopecia in 4 (2.4%) of 168 lesions evaluated at 1 or more years after treatment. Cosmesis at 3 years was excellent for 25 (89.3%) and good for 3 (10.7%) of 28 evaluable lesions; and at 4 years, was excellent for all 6 (100%) evaluable lesions Bhatnagar, 2014).

How would EBT fit into your practice?

  • Personnel:
    • Radiation oncologist
    • Radiation therapist
    • Physicist
  • Treatment:
    • Patient comes into room; portable shield (lead walls not required); machine calibrated and dose parameters set
    • Patient treated
    • Visit takes about 15 minutes twice per week for 8-12 treatments
    • Currently, can be performed in office or at a center

Superficial Radiation: a Different Model

Superficial x-ray therapy (SXRT) has been used by dermatologists for many years and it differs from modern electron beam radiotherapy in that light is the energy source rather than a charged particle. The beam in SXRT is very focused with less collateral tissue damage than EBRT; and the treatment duration is 90 seconds. A retrospective analysis performed on 1715 histologically confirmed primary cutaneous BCC and SCC 2000 and 2010 indicated cumulative recurrence rates for all tumors at 2 and 5 years of 1.9% and 5.0%, respectively.  The recurrence rates for BCC at these evaluations were 2% and 4.2% respectively; and those for SCC were 1.8% and 5.8% (Cognetta, 2012). This approach to treatment for NMSC is appropriate for patients with larger tumors in very cosmetic sensitive areas, those receiving anticoagulants, frail/elderly patients who may not tolerate surgery, and those who refuse surgical intervention.

Dermatologists should be leaders in the use of radiation therapy for the treatment of NMSC.  How do we get there?

  • Develop a method where dermatologists can independently perform EBT and SXRT:
    • Dermatologists are skin cancer experts
    • Dermatologists have historically performed external beam radiotherapy for skin conditions
    • Some dermatologists are currently performing EBT
  • There is a Task Force of Conference of Radiation Control Program Directors:
    • Dermatology is represented
    • Develop guidelines and recommend training for dermatologists in either an independent or hybrid system

 

If we aren’t proactive in advances in skin cancer treatment, then other
specialties will and patients will look elsewhere

 

References

Bhatnagar A. Electronic brachytherapy for the treatment of nonmelanoma skin cancer: results up to 4 years. Int J Radiation Oncol. 2014;90:S756.

Cognetta AB, Howard BM, Heaton HP, Stoddard ER, Hong HG, Green WH. Superficial x-ray in the treatment of basal and squamous cell carcinomas: a viable option in select patients. J Am Acad Dermatol. 2012;67:1235-1241.

Khan L, Breen D, Zhang L, et al. Predictors of recurrence after radiotherapy for non-melanoma skin cancer. Curr Oncol. 2014;21:e326-329.