Simultaneous Integrated Boost in Radiation Therapy: Importance of Number of Fractions

The number of fractions for delivering a radiation therapy boost is a critical aspect from a technical perspective, especially when using simultaneous integrated boost. Two recent trials have provided important insights into this.

2 recent publications on this topic

One trial was reported at Astro 2022, known as the RTOG trial, while the second was published in The Lancet this year. Both studies showed that delivering a concurrent boost (also called simultaneous integrated boost) within the same fraction as radiation therapy is more efficient than sequential boost.

Delivering Concurrent Boost

This method, where 15 fractions of radiation are given, each including an additional boost, has significant advantages. It allows for conservative surgery treatment to be maintained within three weeks and 15 fractions, while effectively delivering the boost.

Technology Required

To accomplish this, advanced technologies like Intensity-Modulated Radiation Therapy (IMRT) and Accelerated Partial Breast Irradiation (APBI) are required. These technologies make it possible to deliver the boost concurrently with standard radiation therapy.

Comparison with Sequential Boost

The results from these trials suggest that the simultaneous integrated boost is comparable to sequential boost in terms of efficacy. Some studies have even shown better cosmetic outcomes and lower late toxicity compared to sequential boost.

Limitations

However, it’s essential to note that escalating the number of boost fractions beyond 15 is currently not feasible with this technique. Therefore, we can currently deliver the boost in 15 fractions, the standard radiation therapy in 14 fractions to the whole breast, and an additional 48 fractions to the tumor bed and node.

Application

These findings are particularly relevant for locally advanced and high-risk patients, as they can complete their treatment within a shorter time frame while still achieving optimal results.