HDR Brachytherapy for Skin Cancers Joseph Lee, M.D., Ph.D. Radiation Oncology Associates Fairfax Hospital
No conflicts of interest
Outline Case examples from Fairfax Hospital Understand radiation s mechanism of action Brachytherapy Indications & contraindications Technique & clinical examples NMSC, CTCL, Merkel cell carcinoma Outcomes & toxicity Summary
87yoM right nose BCC with potential cartilage invasion s/p electron beam therapy 55Gy in 2.5Gy/fx completed Jan 2015. NED 5 mo later in May 2015.
Foot CTCL: Feb 15, 2017
HDR 4Gy x 2 prescribed to 3-4mm Treated 3/2 and 3/3/2017
External beam radiation: X-rays Courtesy of www.varian.com
HDR Brachytherapy: gamma rays
Radiation Oncology Dosing: Gray 1 gray (Gy) = 1 joule (J) / kilogram (K)
XRT: Mechanism of Action Hall & Giaccia's Radiobiology for the Radiologist, 7th ed.
Aberrations Mitotic Catastrophe
Radiation Alone for NMSCs Excellent option for small, well-defined, primary SCCs, especially in older patients and those who are not surgical candidates. One of the major benefits of radiation therapy is its sparing of normal, healthy tissue -- superior cosmetic results for tumors located on or around the lips, nose, and eyelids. Drawbacks associated with the use of RT include the lack of histologic control of tumor margins, high cost compared to other modalities, and the potential short- and long-term side effects associated with radiation. Cutaneous SCCs that recur following RT may behave more aggressively than those that recur after surgery, with higher rates of local recurrence and metastases.
Radiation: Relative Contraindications Patients younger than 40-50 years (2 nd malignancy & cosmesis) Previously irradiated areas (Mohs) Areas prone to repeated trauma (e.g., dorsum of hand, belt line) Poorly blood supply (e.g., below the knee.) High occupational sun exposure Impaired lymphatics Exposed cartilage/bone RT should never be used in patients with basal cell nevus syndrome since it may induce numerous skin cancers that are difficult to manage. Verrucous carcinoma, since several reports have documented anaplastic transformation with subsequent widespread metastases following RT.
GEC-ESTRO Handbook
Radiation Toxicities Acute effects Moist desquamation (resolve in 3-6 wk) Late effects telangiectasias, atrophy, hypopigmentation skin necrosis 3% osteoradionecrosis ~1% chondritis/cartilage necrosis (rare if <3Gy per day) hair & sweat gland loss
GEC-ESTRO Handbook
High Dose Rate Brachytherapy
HDR Brachytherapy Courtesy of Dr. M Kaspar, Boca Raton, FL
GEC-ESTRO Handbook
GEC-ESTRO Handbook
HDR for CTCL
Merkel Cell Carcinoma and XRT Merkel cell tumors are known to be highly radiosensitive Radiotherapy treatment of both the primary site and regional nodes should be considered for patients Roles for XRT in Merkel cell carcinoma adjuvant XRT to improve LRC and OS primary XRT for non-surgical or unresectable patients palliative XRT techniques conventional fractionation schedule, 1.8 2 Gy daily over 5-7 weeks no evidence to suggest a benefit for altered fractionation. External beam & HDR brachytherapy for palliation
XRT for Merkel Cell Carcinoma Radiation should be strongly considered Adjuvant XRT can improve locoregional control and survival 50-66 Gy to primary bed 46-50 Gy to region nodes (60-66 Gy if cln+) Palliative XRT can reduce symptoms in metastatic disease Evidence for definitive radiation treatment is growing In-field control rates 85-100% - need more f/u External beam 50Gy to tumor bed & nodes Evidence for brachytherapy as palliation for in-transit mets HDR Brachytherapy 12Gy in 2 fx achieves 99% lesion local control Majority of patients relapse however
Brachytherapy palliation Garibyan et al, Cancer J 2013 10 MCC pts at Harvard with in-transit cutaneous mets, 2006-2012 Treated 6Gy x 2 with custom surface HDR mold Median f/u 34 mo All mets resolved clinically within a few weeks of therapy 2 of 152 met lesions recurred (99% LC) 80% pt developed in-transit mets out of field 3 pt NED, 3pt alive with disease, 4 died of MCC
Conclusion
External Beam Summary External beam radiation for NMSC achieves high control rates (93-97%) good/excellence cosmesis (81-96%) External beam radiation is well-suited for: definitive therapy for facial and ear lesions, older & nonsurgical patients adjuvant treatment in high-risk NMSC pts & Merkel cell carcinoma Palliation of CTCL 4Gy x 2
Brachytherapy Summary -HDR skin brachytherapy is a convenient, noninvasive, well-tolerated radiation therapy technique for both small and large superficial BCC and SCC skin cancers -HDR brachytherapy achieves excellent local control (94-99%) and good/excellent cosmesis (89-94%) in as little as 6-10 fractions over 2-3 weeks -HDR skin brachytherapy is particularly helpful for elderly, infirm patients, those on blood thinners, or for sites at risk for delayed healing with surgery
Brachytherapy Summary CTCL lesions have excellent response ~100% to short 4Gy x 2 HDR regimens with little to no radiation toxicity Merkel cell in-transit mets achieve 99% LC to 6Gy x 2 HDR regimens
Fairfax Inova Hospital Fair Oaks Inova Hospital Loudoun Inova Hospital Alexandria Inova Hospital Potomac Sentara Hospital Joseph.Lee@inova.org