Clinical Radiation Oncology: Disease Sites and Multidisciplinary Management
What to know
For each major site (head and neck, lung, breast, prostate, GI, CNS, gynecologic, lymphoma, sarcoma, pediatric) you must know the indications for radiotherapy, the standard dose/fractionation, and the sequencing with surgery and systemic therapy. Questions test whether you can place radiotherapy correctly in the multidisciplinary pathway: neoadjuvant vs adjuvant vs definitive vs palliative.
Concepts to master
- Staging drives intent. Early-stage disease often favors single modality (surgery or RT); locally advanced disease favors combined modality.
- Adjuvant RT triggers: positive/close margins, nodal involvement, extracapsular extension, high-grade features, and local recurrence risk thresholds.
- Dose-response by site: e.g., microscopic disease ~45-50 Gy at 1.8-2 Gy/fraction; gross disease higher; palliative courses shorter.
- Omission trials (e.g., de-escalation in selected breast or HPV+ oropharynx) test whether you know when not to treat.
Traps
- Confusing adjuvant sequencing (chemoradiation concurrent vs sequential) - concurrent chemoradiation is standard for many locally advanced head/neck, lung, cervix, and rectal cancers.
- Assuming surgery is always first; in many sites definitive chemoradiation is organ-preserving standard.
- Mixing elective nodal coverage with gross nodal dosing.
Rule of thumb
If a question describes microscopic residual disease after resection, think ~50 Gy in 2 Gy fractions; if it describes unresectable gross disease, think ~60-70 Gy with concurrent radiosensitizer. Match the dose to the burden, not the site name alone.
Worked example
A patient with resected head/neck SCC has a positive margin and extracapsular nodal extension. The question asks the adjuvant approach. Positive margin and ECE are high-risk features → concurrent chemoradiation to ~60-66 Gy, not RT alone at 50 Gy.