Tumour-Specific Growth Rate as a Potential Predictor of Outcomes in Oligoprogressive Disease Treated With Stereotactic Body Radiotherapy

I Navarro-Domenech ¹, J Helou ², S Kuruvilla Thomas ³

⁰Radiation Medicine Program, Princess Margaret Cancer Centre, University Health Network, Toronto, Canada; Radiation Oncology, La Paz Hospital, Madrid, Spain.

Clinical Oncology +

|

July 4, 2025

View abstract on PubMed

Summary

Tumor-specific growth rate (SGR_OP) may predict outcomes in oligoprogressive disease (OPD) treated with stereotactic body radiotherapy (SBRT). Lower growth rates correlate with better overall survival, suggesting SGR_OP as a potential predictive tool.

Area Of Science

Oncology
Radiation Oncology
Medical Physics

Background

Stereotactic body radiotherapy (SBRT) shows promise for oligoprogressive disease (OPD).
Identifying optimal candidates for SBRT in OPD is crucial for treatment efficacy.
Tumor growth rate is a potential factor influencing treatment outcomes.

Purpose Of The Study

To investigate tumor-specific growth rate (SGR_OP) as a predictor of outcomes in patients with OPD treated with SBRT.
To analyze the relationship between SGR_OP and overall survival (OS).
To explore SGR_OP's potential as a predictive tool independent of histology.

Main Methods

Prospective phase II study enrolling patients with ≤5 radiological OPDs.
Retrospective contouring of SBRT-treated metastases on CT scans to calculate SGR_OP (pre- and post-SBRT).
Kaplan-Meier and Cox proportional hazards models used to assess the impact of SGR_OP on OS.

Main Results

Analysis included 35 patients with 55 metastases across gastrointestinal (GI), genitourinary (GU), and breast cancer groups.
Median SGR_OP1 (pre-SBRT growth) was 0.007%/d; median SGR_OP2 (post-SBRT growth) was -0.009%/d.
Lower SGR_OP1 was associated with higher OS rates (71% vs. 47%), though not statistically significant (P=0.35). GI group showed significantly lower 12-month OS (14%) compared to GU and breast groups.

Conclusions

SGR_OP analysis reveals diverse growth rates across cancer types and may predict patient outcomes irrespective of histology.
Further validation is needed to confirm SGR_OP's utility as a predictive tool for SBRT in OPD.
Tumor growth kinetics could offer valuable insights into treatment response and patient prognosis.

Keywords:

Oligoprogressive disease (OPD) outcome predictor patient selection specific growth rate (SGR) stereotactic body radiotherapy (SBRT)

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