What is a typical external beam radiotherapy fraction size and total dose for curative intent in many solid tumors?

• A. 0.5 Gy per fraction to 20 Gy total.
• B. 1.8–2 Gy per fraction, 5 days a week, to about 60–70 Gy total.
• C. 5 Gy per fraction to 100 Gy total.
• D. 3–4 Gy per fraction to 30 Gy total.

Answer: (B)

Fractionation strategy in curative external beam radiotherapy aims to maximize tumor kill while protecting normal tissue. The standard approach uses about 1.8–2 Gy per fraction, given five days a week, for roughly six to seven weeks, totaling around 60–70 Gy. This regimen balances delivering enough total dose to control many solid tumors with sparing late-responding normal tissues by allowing repair between fractions. If the dose per fraction is too small, the total dose may need to be unrealistically high to achieve tumor control; if it’s too large, normal tissues incur unacceptable late toxicity. A schedule like 60–70 Gy in ~30–35 fractions (about 6–7 weeks) represents the conventional, widely used curative approach for many solid tumors.