Radiosensitizing Properties of Chemotherapy Agents

Introduction to Radiosensitization

The American Society of Clinical Oncology and the European Society for Medical Oncology (ESMO) guidelines support the use of etoposide and platinum agents as radiosensitizers in concurrent chemoradiotherapy regimens for limited-stage small cell lung cancer (LS-SCLC) and stage III non-small cell lung cancer (NSCLC) 1, 2, 3, 4, 6

ESMO guidelines recommend cisplatin combined with etoposide, vinorelbine, or other vinca alkaloids for concurrent radiotherapy in stage III NSCLC, with high-quality evidence supporting its efficacy when administered with radiation 4, 5, 6
The radiosensitizing effect of etoposide is well-established when used in platinum-based doublets during concurrent radiation therapy, according to the American College of Clinical Oncology 4, 6

ESMO guidelines state that there are no firm conclusions supporting single-agent carboplatin as a radiation sensitizer, with low-quality evidence and weak recommendations 4, 5, 7, 8, 6
Single-agent carboplatin failed to improve survival when given concurrently with radiotherapy in two prospective randomized trials in stage III NSCLC, as reported by the European Society for Medical Oncology 4, 5
Carboplatin combined with etoposide may be offered as systemic therapy concurrent with radiation for patients with LS-SCLC who have contraindications to cisplatin, with strong support despite low-quality evidence from the American Society of Clinical Oncology 1, 2, 3
In clinical practice, carboplatin plus etoposide with concurrent radiotherapy showed comparable efficacy to cisplatin-based regimens in LS-SCLC, with no significant differences in response rates or survival outcomes, according to the American College of Clinical Oncology 1, 3

When concurrent chemoradiotherapy is indicated, the choice should follow an algorithm where first-line treatment is cisplatin plus etoposide with concurrent radiation, with high-quality evidence and strong recommendations from the American Society of Clinical Oncology and ESMO 1, 2, 3, 6
For cisplatin-intolerant patients, carboplatin plus etoposide with concurrent radiation is an acceptable alternative with similar efficacy but more myelosuppression, as recommended by the American Society of Clinical Oncology and ESMO 1, 2, 3
Single-agent carboplatin as a radiosensitizer should be avoided due to insufficient evidence of benefit, according to ESMO guidelines 4, 5, 7, 8, 6
The radiosensitizing benefit of carboplatin appears dependent on combination with other agents, particularly etoposide, rather than as monotherapy, with low-quality evidence from the American Society of Clinical Oncology and ESMO 1, 4
Carboplatin-etoposide regimens result in more myelosuppression compared to cisplatin-based therapy, while cisplatin causes more nausea, vomiting, neurotoxicity, and nephrotoxicity, as reported by the American College of Clinical Oncology 1, 3