The Fellow on Call: The Heme/Onc Podcast

Episode 130: Testicular Cancer Series, Pt 4 – Role of Radiation Oncology

Date: March 5, 2025
Host: Rouleaux University Medical Center
Guests: Dr. Amar Kishan, Professor & Executive Vice Chair, Radiation Oncology, UCLA

Episode Overview

This episode explores the role of radiation oncology in the management of testicular cancer, with a focus on seminoma, featuring Dr. Amar Kishan, a leading radiation oncologist. The discussion delves into modern treatment paradigms, evolving evidence, patient selection, long-term risks, and emerging therapies. The conversation is highly multidisciplinary, aiming to bridge the communication between medical oncology, urology, and radiation oncology for the benefit of a predominantly trainee and provider audience.

Key Discussion Points & Insights

1. Pre-Visit Workup & The Role of Imaging

• Recommended workup: CT imaging for accurate staging is essential, particularly for seminomas, along with serum tumor markers (β-hCG, LDH, AFP). Fertility discussion documentation is also valuable.
• Quote:

  "For us it's going to be CT imaging... key to staging testicular cancer... Also helpful to have tumor markers checked like beta-hcg, LDH, AFP... Fertility is always helpful, and we may circle back to that."
  — Dr. Kishan [03:24]

2. Radiation Therapy in Stage I Seminoma – Evolution, Process, & Contemporary Role

• Historical context: Radiation has been used since the 1920s due to high radiosensitivity of seminoma.
• Shift to less intensive treatment: The field has moved towards de-escalation (lower doses, smaller fields), and even omission (active surveillance for most patients).
• Current protocol: When chosen, modern radiation is given to the para-aortic field only (T11/T12 to L5/S1, 20 Gy over 10 fractions—two weeks of daily treatments).
• Special circumstances: If prior pelvic surgery (e.g., orchiopexy), may consider a larger ‘dog leg’ field.
• Tolerability: Main acute effects are nausea, fatigue, and occasional diarrhea, all typically mild and manageable.
• Surveillance preference: Most stage I seminoma patients are managed with surveillance—the risk of relapse is low and survival remains excellent even after relapse. MRI-based, lower-intensity surveillance may become more common but hasn’t entered broad practice due to logistical issues.
• Risk stratification: Tumor size and rete testis invasion are traditional risk factors; new nomograms split this further. Only the highest risk subset (>5cm tumors + invasion) might justify adjuvant therapy up front.
• Quote:

  "Surveillance is the preferred option for the vast majority of stage one seminoma patients... The risk of recurrence is only 12 to 20% which is very low."
  — Dr. Kishan [07:46]

3. Role in Stage II Seminoma – Nuance, Guidelines, and Field Reduction

• Stage II meta-analysis: Prior studies suggest chemotherapy may be superior for >2cm (stage IIB), but for stage IIA (≤2cm) radiation is guideline-supported, especially in the US.
• Modern practice: Precise CT-based staging allows safer field reduction (no more routine mediastinal irradiation).
• Protocol: Dog-leg field (para-aortic + ipsilateral pelvic nodes, 20 Gy), with boosts to involved nodes (additional 10 Gy for IIA, 16 Gy for IIB).
• Quote:

  "For stage 2A, seminoma, radiation is a great option... In Europe it's just stage 2A that it's a preferred modality."
  — Dr. Kishan [12:08]

4. Fertility, Hormonal, and Long-Term Toxicity Counseling

• Fertility:
  • Spermatogonia are highly radiosensitive—even small amounts impair spermatogenesis.
  • Lead shields (clam shells) are used to protect the remaining testis, usually keeping exposure below permanent harm threshold.
  • Sperm banking is recommended. Strict contraception is advised for 6–12 months after treatment due to possible DNA mutations.
• Hormones:
  • Leydig (testosterone-producing) cells are radioresistant; no significant hypogonadism expected.
• ED & pelvic nerves:
  • Erectile dysfunction is not expected—fields are remote from neurovascular structures around the prostate.
• Long-term risks:
  • Secondary malignancy: Increased risk (estimated 2–7%); field and dose reductions aim to lessen this.
  • Cardiovascular toxicity: Relative risks increased, possibly from radiation to pancreas/renal hilum (leading to diabetes, hypertension). These risks remain clinically relevant but have diminished with modern techniques.
• Quotes:

  "Sperm banking... is always a good idea... After radiation, they should actually use contraception very religiously for six to twelve months, because the sperm may have incurred mutations."
  — Dr. Kishan [15:08]
  "We don't really expect the patient to have any significant hypogonadism incurred from this part of the treatment."
  — Dr. Kishan [16:14]
  "The two major long-term morbidities are secondary malignancies... and cardiovascular toxicity."
  — Dr. Kishan [19:13]

5. Proton Therapy for Testicular Cancer – Theory vs. Clinical Reality

• Theory: Protons (charged particles) deposit energy with no exit dose (Bragg peak), sparing more normal tissue than photons (X-rays).
• Reality: Physical dose plans look better for protons, but actual clinical outcome data is lacking—no proven superiority except in select scenarios.
• Accessibility: It’s reasonable to consider if available, but not justified at all costs.
• Quote:

  "Most radiotherapy is photon... Proton beams have a physical property called the Bragg peak... That underlies the premise of why proton beam therapy may lead to reduced toxicity...but we don’t have proof that it’s better."
  — Dr. Kishan [22:10]

6. Emerging Research and Future Directions

• Combination therapy (chemo + reduced field RT):
  • SAKK and Royal Marsden trials: single-cycle carboplatin plus reduced field radiation shows high progression-free survival in stage II seminoma—may define future standard, especially for stage IIA.
  • Further trials are reducing dose and fields even further, and incorporating novel risk stratification (e.g., microRNAs, PET imaging).
• Surgery: Recent trials have explored surgery alone for stage II, but recurrence rates are higher than with chemo/radiation, though possible advantage is less long-term toxicity.
• Quote:

  "The major topic of excitement is the role of combination therapy for stage two seminoma... The SAK 0110 trial... involved nodal radiotherapy, which is like a substantial reduction in radiation field size. Their three-year progression-free survival was like 93.7%, which is really good..."
  — Dr. Kishan [25:48]

7. Memorable and Lighthearted Moments

• Dr. Kishan reveals he’s a passionate pro wrestling fan:

  "I’m actually a huge fan of professional wrestling—to the extent that for my recent birthday, my gift was ringside tickets to the Netflix debut of WWE Raw..."
  — Dr. Kishan [02:24]

• Hosts joke about The Rock’s size and the rarity of this fun fact among guests.
• Light, upbeat tone maintained throughout, contributing to an engaging, collegial learning environment.

Notable Quotes & Timestamps

• "For us it's going to be CT imaging... and tumor markers checked like beta hcg, ldh, afp... and fertility... in this largely young population." — Dr. Kishan [03:24]
• "Surveillance is the preferred option for the vast majority of stage one seminoma patients." — Dr. Kishan [07:46]
• "For stage 2A, seminoma, radiation is a great option... for stage 2B... they prefer chemotherapy." — Dr. Kishan [12:08]
• "I tell my patients that they should actually use contraception very religiously for six to twelve months... the sperm actually may have survived but have incurred mutations." — Dr. Kishan [15:08]
• "We don't really expect the patient to have any significant hypogonadism incurred from this part of the treatment." — Dr. Kishan [16:14]
• "The two major things that drive radiation de-escalation are secondary malignancies and cardiovascular toxicity." — Dr. Kishan [19:13]
• "Most radiotherapy is photon... but with proton beams, there's very little exit dose... But we don't have proof that it's better." — Dr. Kishan [22:10]
• "The major topic of excitement is the role of combination therapy for stage two seminoma... SAKK... involved nodal radiotherapy... three-year progression-free survival was like 93.7%." — Dr. Kishan [25:48]

Timestamps for Key Segments

• [03:24] — Preparation for radiation oncology consultation
• [04:56] — Modern radiation protocol for stage I seminoma, surveillance, new risk tools
• [10:44] — Meta-analysis and guidelines for stage II seminoma, radiotherapy vs. chemotherapy
• [14:31] — Fertility, hormonal, counseling during RT
• [17:22] — Erectile dysfunction, secondary malignancy, cardiovascular risks
• [22:10] — Protons vs. photons: the evidence and practical considerations
• [25:48] — Cutting-edge research: combo therapy, reduced field trials, and ongoing studies
• [29:12] — Brief mention of surgical series and recurrence rates

Concluding Thoughts

• Emphasis on multidisciplinary care and the importance of understanding perspectives and practices across specialties.
• Final reflection on the need to minimize long-term toxicity as patients are young and may live for many decades post-treatment.

Quote:

"It's very important to have these kind of multidisciplinary discussions, all benefit from learning from one another... It's always a pleasure to do these multi disciplinary discussions."
— Dr. Kishan [30:00]

For trainees and providers, this episode provides a nuanced, practical overview of the evolving landscape of radiotherapy in testicular cancer, balancing evidence, frontline experience, and ultimately, patient-centered considerations.