P U R P O S E
High dose rate electronic brachytherapy (EBX) 

provides a non-surgical treatment option for non-
melanoma skin cancer (NMSC). This matched-pair 

cohort study compared the outcomes of treatment 
with EBX to those of Mohs micrographic surgery 
(MMS) in patients with NMSC.

M E T H O D S
All patients who had already received EBX for 
NMSC at 4 clinical sites and met the eligibility 

criteria were invited to participate. EBX was 
previously administered using the Xoft® Axxent® 
Electronic Brachytherapy System® (Xoft, Inc., A 
Subsidiary of iCAD, Inc. San Jose, CA).  Standard 
surface applicators (Xoft, Inc.) included sizes 
10, 20, 35, and 50 mm in diameter and EBX was 
administered in 8-10 fractions twice per week, with a dose per fraction of 4, 4.5 or 5 
Gy, to an average depth of 3mm. MMS was previously performed by clinicians who 
had completed Mohs fellowship training, and surgeries were conducted according to 
guidelines of the ACMS. The EBX participants were individually matched with MMS 
patients based on patient age, lesion size (≤1cm, >1cm ≤2cm, >2cm ≤3 cm) type, 
and location (head, nose, torso, upper extremity, lower extremity), and treatment 
dates. Eligibility criteria included: Completion of EBX or MMS for NMSC ≥3 years prior 
to enrollment; age >40 years; pathological diagnosis confirmed (SCC, BCC) prior to 
treatment; cancer stage 0-2. Exclusion criteria included: Target area adjacent to a burn 
scar; surgical resection of the cancer prior to EBX; known metastatic disease. Data were 
collected prospectively at an office visit, during which patients were clinically evaluated 
by the physician who had conducted the EBX or MMS, and each participant completed 
a questionnaire.

RESULTS
The 369 patients (188 in the EBX 
treatment group and 181 in the 

MMS treatment group) had 416 
lesions (208 in the EBX group and 
208 in the MMS group), including 
226 basal cell carcinomas 
(BCC) and 190 squamous cell 
carcinomas (SCC). Most patients 
were Caucasian (98.9% and 
99.5%) and male (65.4% and 
66.3%) of median age 80.7 (EBX) 
and 76.8 years (MMS). Most 
lesions were size >1 cm and ≤2 
cm, and located on the head 
(Ear/Eyelid/Face/Neck/Lip/Scalp), 
59.2% in each group. At follow up, 66.7% of EBX and 68.8% showed a relatively invisible 
scar (p=ns).  99.5% of EBX and 100.0% of MMS-treated lesions were recurrence-free 
(p=ns). Physicians rated cosmesis as “Excellent” or “Good” in 97.6% and 95.7% of EBX-
treated and MMS-treated lesions respectively (p=ns). 

C O N C LU S I O N
Recurrence rates and patient reported outcomes with EBX and MMS were similar at a 
mean of 3.4 years following treatment of NMSC.

Comparison of Electronic Brachytherapy and Mohs Micrographic Surgery for the 
Treatment of Early-Stage Non-Melanoma Skin Cancer: A Matched Pair Cohort Study

a. Rakesh Patel, MD; b. Robert Strimling, MD; c. Stephen Doggett, MD; d. Mark Willoughby, MD and Erick Mafong, MD; e. Kenneth Miller, MD, PC; f. Lawrence Dardick, MD

a. Good Samaritan Radiation Oncology, Los Gatos, CA; b. Strimling Dermatology, Laser Vein Institute, Las Vegas, NV;  c. Aegis Oncology, Tustin, CA; d. San Diego Dermatology and Laser Institute, San Diego, CA; e. Miller Dermatology, Los Gatos, CA; f. Berman Skin Institute, Placerville, CA

Table 1. Patient Demographics at Time of Treatment

Variable EBX MMS
Number of Patients (%) 188 181
Age (years) Median 80.7 76.8

Range 61.1 – 98.0 51.4 – 98.4
Gender Male 123 (65.4%) 120 (66.3%)

Female 65 (34.6%) 61 (33.7%)
Ethnicity Caucasian/Non-Hispanic 186 (98.9%) 180 (99.5%)

African-American 0 (0.0%) 1 (0.5%)
Asian/Pacific Islander 2 (1.1%) 0 (0.0%)

Prior skin cancer Prior skin cancer 147 (78.2%) 136 (75.1%)
Types: Melanoma 13 (6.9%) 8 (4.4%)

BCC 135 (71.8%) 114 (63.0%)
SCC 105 (55.9%)  97 (53.6%)
BSC 1 (0.5%) 0 (0.0%)

Prior surgery or treatment of another lesion 57 (30.3%) 124 (68.5%)
EBX=electronic brachytherapy; MMS=Mohs micrographic surgery;  
BCC=basal cell carcinoma;  
SCC=squamous cell carcinoma; BSC=basosquamous carcinoma

Table 2. Lesion Characteristics at Time of Treatment

Variable EBX MMS
Number of Lesions (%) 208 208
Histopathology BCC 113 (54.3%) 113 (54.3%)

SCC 95 (45.7%) 95 (45.7%)
Cancer Staging1 Stage 0: Tis, N0, M0 101 (48.6%) 76 (36.5%)

Stage 1: T1, N0, M0  103 (49.5%) 129 (62.0%)
Stage 2: T2, N0, M0 &  

≤ 4 cm in diameter  
4 (1.9%) 3 (1.4%)

Lesion Size (cm) ≤ 1 cm 57 (27.4%) 57 (27.4%)
> 1 cm and ≤ 2 cm 146 (70.2%) 146 (70.2%)
> 2 cm and ≤ 3 cm 5 (2.4%) 5 (2.4%)

Lesion Location Head 5 (2.4%) 5 (2.4%)
Ear 10 (4.8%) 10 (4.8%)

Eyelid 5 (2.4%) 5 (2.4%)
Face/Neck 72 (34.6) 72 (34.6)

Lip 4 (1.9%) 4 (1.9%)
Scalp 14 (6.7%) 14 (6.7%)
Nose 33 (15.9%) 33 (15.9%)
Torso 12 (5.8%) 12 (5.8%)

Lower Extremity 23 (11.1%) 23 (11.1%)
Upper Extremity 30 (14.4%) 30 (14.4%)

EBX=electronic brachytherapy; MMS=Mohs micrographic surgery; BC-
C=basal cell carcinoma; SCC=squamous cell carcinoma; T=tumor; N=nodes 
(lymph); M=metastases; G=grade  
1. Cancer Staging System of the American Joint Committee on Cancer

Table 3. Treatment Characteristics for Electronic Brachytherapy (EBX)

Number of Lesions (%) 208
Applicator Size (mm) 10 mm  78 (37.5%)

20 mm 103 (49.5%)
35 mm 25 (12.0%)
50 mm 2 (1.0%)

Total Received Dose 32 Gy 5 (2.4%)
36 Gy 1 (0.5%)
40 Gy  207 (99.5%)
50 Gy 1 (0.5%)

Number of Fractions 8/8 198 (95.2%)
10/10 10 (4.8%)

Dose per Fraction 4 Gy 14 (6.7%)

4.5 Gy 1 (0.5%)
5 Gy 193 (92.8%)

Table 4. Treatment Characteristics for Mohs Micrographic Surgery (MMS)

Number of Lesions (%) n= 208
Stages/levels required for 
clear margins

1 177 (85.1%)
2 30 (14.4%)
3 1 (0.5%)

Closure method Surgical Closure 192 (92.3%)
Secondary Intension 16 (7.7%)

Table 5. Primary Endpoint: Absence of Local Recurrence at Followup Visit

EBX MMS
Number of Lesions (%) 208 208
Absence of Local Recurrence 207 (99.5%) 208 (100.0%)

95% CI: 97.4% - 100% 98.2% - 100%
p-value (Fisher’s Exact Test): 1.000

Follow-up time (years) Mean ± Std 3.3 ± 0.4 3.5 ± 0.5
Median 3.2 3.4

Range 2.6 – 4.3 2.3 – 5.0

Table 6. Long-Term Toxicities Present at Followup Visit

EBX MMS
Number of Lesions (%) 208 208
No changes, relatively invisible scar 138 (66.7%) 143 (68.8%)
Late toxicities:

Hypopigmentation 124 (59.6%) 109 (52.4%)
Hyperpigmentation 11 (5.3%) 4 (1.9%)
Erythematous scar 6 (2.9%) 15 (7.2%)

Telangiectasia 65 (31.4%) 23 (11.1%)
Hair loss 8 (3.9%) 7 (3.4%)
Fibrosis 3 (1.4%) 2 (1.0%)
Atrophy 12 (5.8%) 9 (4.3%)

Loss of subcutaneous tissue 7 (3.4%) 6 (2.9%)
Hypertrophy (excessive fibrosis) or Keloid 0 (0.0%) 3 (1.4%)

Poor healing, ulceration, erosion 4 (1.9%) 0 (0.0%)
EBX=electronic brachytherapy; MMS=Mohs micrographic surgery

Table 7. Secondary Endpoint: Cosmesis Grade at Follow-up Visit

EBX MMS
Number of Lesions (%) 208 208
Clinician Cosmetic Grade Excellent/Good 203 (97.6%) 199 (95.7%)

95% CI: 94.5% - 99.2% 92.0% - 98.0%
p-value (χ2 test): 0.277

Clinician Cosmesis 
Grade1

Excellent 133 (63.9%) 142 (68.3%)
Good 70 (33.7%) 57 (27.4%)

Fair 1 (0.5%) 9 (4.3%)

Poor 4 (1.9%) 0 ( 0.0%)
Subject Cosmesis Grade1 Excellent 140 (67.3%) 148 (71.1%)

Good 48 (23.1%) 50 (24.0%)
Fair 15 (7.2%) 10 (4.8%)

Poor 5 (2.4%) 0 (0.0%)
(χ2 p-value = 0.277). Cosmesis ratings by patients were “excellent” or 
“good” in 90% of EBT-treated sites and 95% of MMS-treated sites
1. Adapted from Cox et al.

Table 8. Results of Patient Satisfaction Questionnaire at Followup Visit

Total Score EBX n=208 MMS n=208
Mean ± Std 54.0 ± 9.0 56.0 ± 5.3
Median [Range] 58.0 [10 – 60] 59.0 [38 – 60]
Individual Questions2

Treatments were convenient 
(5=strongly agree)

4.3 ± 1.1 
5.0 [0 – 5]

4.7 ± 0.6 
5.0 [2 – 5]

Satisfied with how well treatment worked 
(5=strongly agree)

4.5 ± 1.0 
5.0 [0 – 5]

4.8 ± 0.5 
5.0 [1 – 5]

Satisfied with appearance of the treated area 
(5=strongly agree)

4.4 ± 1.0 
5.0 [0 – 5]

4.6 ± 0.7 
5.0 [2 – 5]

If another cancer, would use same treatment 
(5=strongly agree) 

4.1 ± 1.4 
5.0 [0 – 5]

4.6 ± 0.7 
5.0 [1 – 5]

Have not had any skin problems with treated area 
(5=strongly agree) 

4.5 ± 1.2 
5.0 [0 – 5]

4.7 ± 0.6 
5.0 [1 – 5]

Since treatment, frustrated about appearance of treated site 
(5=strongly disagree)

4.5 ± 1.1 
5.0 [0 – 5]

4.6 ± 1.0 
5.0 [0 – 5]

Since treatment, embarrassed about appearance of treated site 
(5=strongly disagree)

4.6 ± 0.9 
5.0 [0 – 5]

4.7 ± 0.7 
5.0 [1 – 5]

Since treatment, depressed about appearance of treated site 
(5=strongly disagree)

4.5 ± 1.1 
5.0 [0 – 5]

4.6 ± 0.8 
5.0 [0 – 5]

Treatment prevented me from participating in daily activities 
(5=strongly disagree)

4.6 ± 0.9 
5.0 [0 – 5]

4.6 ± 0.9 
5.0 [0 – 5]

Treatment made it hard to work or do what I enjoy 
(5=strongly disagree)

4.7 ± 0.7 
5.0 [0 – 5]

4.6 ± 0.8 
5.0 [0 – 5]

Would recommend treatment to others 
(5=strongly agree)

4.4 ± 1.3 
5.0 [0 – 5]

4.7 ± 0.7 
5.0 [0 – 5]

Always followed instructions related to care of treated area 
(5=strongly agree)

4.9 ± 0.4 
5.0 [3 – 5]

4.7 ± 0.5 
5.0 [2 – 5]

Std=standard deviation
2. A score of 5 represents the maximum positive or favorable response to each question. 


	FC17PosterXoftPatelComparison.pdf