Multiple Choice Questions: Radiotherapy for Squamous and Basal Cell Carcinoma
Question 1: Indications for Primary Radiotherapy
A 72-year-old patient with a 1.5 cm basal cell carcinoma on the nasal bridge refuses surgery. Which statement about radiotherapy as primary treatment is MOST accurate?
A) Radiotherapy is contraindicated due to high risk of radionecrosis over bone B) Radiotherapy achieves 5-year cure rates of 91.3% for primary BCC and is an appropriate treatment choice C) Radiotherapy should only be used if the patient is under 60 years old D) Surgery must be performed first before considering radiotherapy
Correct Answer: B
Explanation: Radiotherapy is highly effective for primary basal cell carcinoma, achieving 5-year cure rates of 91.3% and is the treatment of choice for high-risk disease in patients unwilling or unable to tolerate surgery. 1 While the nasal bridge was historically associated with radionecrosis risk, RT can be used successfully on facial sites including the nose with proper technique. 1 The guideline recommendation is to generally reserve RT for patients older than 60 years due to long-term sequelae concerns, not younger patients. 1, 2 RT is appropriate as primary treatment without requiring surgery first. 1
Question 2: Absolute Contraindications to Radiotherapy
Which patient has an ABSOLUTE contraindication to radiotherapy for basal cell carcinoma?
A) A 55-year-old with a history of extensive sun exposure B) A 68-year-old solid organ transplant recipient on immunosuppression C) A 45-year-old with basal cell nevus syndrome (Gorlin syndrome) D) A 70-year-old with a BCC on the trunk
Correct Answer: C
Explanation: Radiotherapy is absolutely contraindicated in patients with genetic conditions predisposing to skin cancer, such as basal cell nevus syndrome and xeroderma pigmentosum, due to increased sensitivity to ionizing radiation and risk of inducing further tumors. 1, 2 RT is also absolutely contraindicated in connective tissue diseases like scleroderma and lupus. 1, 2 History of sun exposure alone is NOT a contraindication. 2 Immunosuppression alone is not an absolute contraindication, though it increases risk and requires careful consideration. 2 Trunk location is a relative contraindication as low-risk regions are not usually treated with RT, but this is not absolute. 1
Question 3: Radiotherapy Fractionation Schedules
For a 2.5 cm squamous cell carcinoma of the cheek in a 75-year-old surgical non-candidate, which fractionation schedule is MOST appropriate according to NCCN guidelines?
A) 35 Gy in 5 fractions over 5 days B) 50 Gy in 15 fractions over 3 weeks C) 55 Gy in 20 fractions over 4 weeks D) 30 Gy in 10 fractions over 2 weeks
Correct Answer: C
Explanation: For tumors ≥2 cm, NCCN guidelines recommend 66 Gy in 33 fractions over 6-6.6 weeks OR 55 Gy in 20 fractions over 4 weeks. 1 Protracted fractionation is associated with improved cosmetic results. 1 The 35 Gy in 5 fractions schedule is only appropriate for tumors <2 cm. 1 Field margins should be 1.5-2 cm for tumors ≥2 cm. 1 The 30 Gy option is not listed in standard NCCN fractionation schedules for curative intent. 1
Question 4: Radiotherapy vs Surgery Efficacy
A dermatology resident asks about cure rates comparing radiotherapy to surgery for basal cell carcinoma. What is the MOST accurate statement based on guideline evidence?
A) Radiotherapy and surgery have equivalent 5-year cure rates B) Radiotherapy has higher recurrence rates (7.5%) compared to surgery (0.7%) C) Radiotherapy is superior to surgery for cosmetic outcomes in all cases D) Surgery and radiotherapy have identical long-term complication profiles
Correct Answer: B
Explanation: Radiotherapy results in higher recurrence rates than surgery (7.5% vs 0.7%) and poorer cosmetic outcomes. 2 A randomized trial comparing RT to cryotherapy showed 2-year cure rates of 96% for RT, demonstrating good but not perfect efficacy. 1 While RT can achieve excellent cosmesis when properly applied, surgery generally provides superior outcomes. 1 Importantly, 56% of recurrences in primary BCC occur more than 5 years after RT, necessitating long-term follow-up. 2 RT achieves 5-year cure rates of 91.3% for primary BCC, which is good but lower than optimal surgical outcomes. 1
Question 5: Adjuvant Radiotherapy Indications
A 62-year-old undergoes Mohs surgery for a high-risk squamous cell carcinoma with substantial perineural invasion identified on pathology. Margins are clear. What is the MOST appropriate next step?
A) No further treatment needed since margins are clear B) Re-excision with wider margins C) Adjuvant radiotherapy to the local tumor site D) Systemic chemotherapy
Correct Answer: C
Explanation: Adjuvant radiotherapy is indicated for substantial perineural involvement in squamous cell carcinoma, even with clear margins, as primary cSCC with concerning perineural invasion is at high risk for regional or distant metastasis. 1, 3 Adjuvant RT is also indicated for positive margins after MMS/CCPDMA and regional lymph node involvement. 3 The typical dose for postoperative adjuvant therapy is 50 Gy in 20 fractions over 4 weeks or 60 Gy in 30 fractions over 6 weeks. 1 For regional disease with extracapsular extension in head and neck, 60-66 Gy over 6-6.6 weeks is recommended. 1 Clear margins alone do not eliminate the need for adjuvant therapy when high-risk features like substantial perineural invasion are present. 1
Question 6: Radiotherapy for Recurrent Disease
A 70-year-old presents with a basal cell carcinoma that recurred 3 years after previous radiotherapy to the same site. What is the MOST appropriate treatment approach?
A) Repeat radiotherapy with higher dose B) Surgical excision (RT is contraindicated) C) Topical imiquimod therapy D) Observation with close follow-up
Correct Answer: B
Explanation: Radiotherapy is absolutely contraindicated in the re-treatment of BCC that has recurred following previous RT to the same field due to cumulative tissue damage risk. 1, 2 RT is effective for surgically recurrent BCC (recurrence after surgery), achieving 5-year cure rates of 90.2%. 1 However, radiorecurrent disease requires surgical management. 1 Topical therapies are inadequate for recurrent disease, which represents high-risk pathology. 1 Observation is inappropriate as recurrent BCC requires definitive treatment. 1
Question 7: Radiotherapy Field Margins
For a 1.2 cm primary squamous cell carcinoma being treated with electron beam radiotherapy, what field margin is MOST appropriate?
A) 0.5 cm margin B) 1-1.5 cm margin C) 2-3 cm margin D) No margin needed with electron beam
Correct Answer: B
Explanation: For tumors <2 cm, field margins should be 1-1.5 cm. 1 When using electron beam, wider field margins are necessary than with orthovoltage x-rays because of the wider beam penumbra. 1 Tighter field margins can be used with electron beam adjacent to critical structures if lead skin collimation is used. 1 For tumors ≥2 cm, margins should be 1.5-2 cm. 1 Bolus is necessary when using electron beam to achieve adequate surface dose. 1 Electron beam doses are specified at 90% of maximal depth dose. 1
Question 8: Age Considerations for Radiotherapy
A 52-year-old patient with a 1.8 cm basal cell carcinoma on the lower eyelid is not a surgical candidate due to severe bleeding disorder. The patient requests radiotherapy. What is the MOST important counseling point?
A) Radiotherapy is absolutely contraindicated under age 60 B) Radiotherapy is generally reserved for patients >60 years due to long-term sequelae concerns, but can be considered in non-surgical candidates C) Age is irrelevant to radiotherapy decision-making D) Radiotherapy should only be offered to patients over 75 years old
Correct Answer: B
Explanation: Radiotherapy is generally reserved for patients older than 60 years due to concerns about long-term sequelae, but can be considered for non-surgical candidates at any age after careful discussion of risks and benefits. 1, 2 The age guideline is a relative, not absolute, contraindication. 2 RT can be used successfully on peri-orbital skin with proper technique. 1 Long-term sequelae include secondary malignancies and chronic tissue changes, which are more concerning in younger patients with longer life expectancy. 2 The decision should weigh the patient's bleeding disorder against age-related concerns. 1
Question 9: Radiotherapy for Verrucous Carcinoma
A 68-year-old presents with a biopsy-proven verrucous carcinoma on the plantar foot. The patient refuses surgery. What is the MOST appropriate recommendation regarding radiotherapy?
A) Radiotherapy is the preferred treatment for verrucous carcinoma B) Radiotherapy is contraindicated due to increased metastatic risk C) Radiotherapy and surgery have equivalent outcomes for verrucous carcinoma D) Radiotherapy should be combined with chemotherapy
Correct Answer: B
Explanation: Verrucous carcinoma is excluded from radiotherapy because several reports document an increased metastatic risk after RT in patients with this generally low-grade malignancy. 1 Additionally, the genitalia, hands, and feet are excluded from RT for non-melanoma skin cancers. 1 Low-risk regions of trunk and extremities are not usually treated with RT. 1 Surgery remains the treatment of choice for verrucous carcinoma. 1 This represents an absolute contraindication based on documented increased metastatic potential after radiation. 1
Question 10: Cosmetic Outcomes with Radiotherapy
A 78-year-old asks about cosmetic outcomes comparing radiotherapy to surgery for a 1.5 cm basal cell carcinoma on the cheek. What is the MOST evidence-based response?
A) Radiotherapy always provides superior cosmetic outcomes to surgery B) Surgery always provides superior cosmetic outcomes to radiotherapy C) Protracted fractionation RT is associated with improved cosmetic results, with 92.62% rated as good/acceptable D) Cosmetic outcomes are identical between RT and surgery
Correct Answer: C
Explanation: Protracted fractionation is associated with improved cosmetic results, with cosmetic outcomes evaluated as "good" or "acceptable" in 92.62% of RT-treated lesions. 1, 4 When properly applied, RT can result in excellent cosmesis. 1 More than 90% of patients reported good or excellent aesthetic outcomes from radiotherapy. 5 However, one randomized trial showed surgery had superior efficacy and cosmetic outcomes compared to RT. 6 The key is that RT details matter—proper technique and fractionation are essential to achieve high cure rates and good cosmesis. 1 Head and neck generally tolerates RT well. 1