Adjuvant Therapy for Cancer: When and Why?

Adjuvant therapy is systemic treatment (chemotherapy, hormonal, targeted, immunotherapy) or radiation given after primary curative treatment (usually surgery) to eliminate micrometastatic disease and reduce recurrence risk.

Indications

• High recurrence risk – based on stage, grade, lymphovascular invasion, margins, molecular markers.
• Specific cancer types – standard for many breast, colon, lung, gastric, pancreatic, melanoma, ovarian cancers.
• Positive margins or nodes – adjuvant chemoradiation (rectal, pancreatic).

Decision Factors

• Tumor biology (ER/PR/HER2, MSI, KRAS, PD-L1, genomic assays like Oncotype DX).
• Patient fitness, comorbidities, preferences.
• Benefit vs. toxicity (e.g., chemo benefit small in low-risk early breast cancer).

Timing

Typically starts 4–12 weeks post-surgery once healed. Duration: 3–6 months (chemo), 5–10 years (endocrine).

Neoadjuvant vs. Adjuvant

Neoadjuvant = before surgery (downstaging, assess response). Adjuvant = after. Some cancers use both (e.g., breast, rectal).