Changes in functional status associated with radiation for prostate cancer in older veterans.

Background: Although older men value maintaining independence and avoiding functional decline, little is known about their functional trajectories with receipt of prostate radiation.

Methods: We performed a retrospective cohort study including veterans age 65+ with localized prostate cancer who resided in a VA nursing facility while receiving prostate radiation from 2005 to 2015. We evaluated the change in Minimum Data Set (MDS) activities of daily living (ADL) score during 6 months from the start of treatment. Because prior studies have shown Charlson Comorbidity Index (CCI) to be a strong predictor of treatment-related toxicity, analysis included interaction with CCI.

Results: We identified 487 patients with median age 73 (range 65-94). For the average patient in our cohort, the predicted MDS-ADL score worsened from 2.9 (95% CI 2.4-3.6) at the start of radiation to 3.8 (95% CI 3.1-4.8) at 3 months and then 4.5 (95% CI 3.5-5.7) at month 6. Patients with greater comorbidity (CCI ≥ 4) had worse functional outcomes in months 0-3 compared to patients with less comorbidity (CCI 0-3). MDS-ADL score worsened by 1.9 in the CCI ≥4 patients compared to 0.3 in the CCI 0-3 group During months 3-6, patients in both Charlson groups experienced similar worsening of MDS-ADL score.

Conclusions: In a vulnerable population of older patients with localized prostate cancer, radiation was associated with a decline in functional independence. Patients with higher comorbidity experienced more severe functional decline within the first 3 months of radiation therapy. In all comorbidity levels, functional status had not returned to baseline by 6 months.