Between 2014 and 2020, 1172 patients were treated with SRT on oligometastatic sites. Patients and
treatment characteristic are shown in table 1.
Best local response during
follow up according to RECIST criteria v 1.1 was as follow: complete response
425 patients (36.3%); partial response 533 (45.5%); stable disease 194 (16.6%);
progressive disease 20 (1.7%)
After a median follow up of
20.3 months, 208 patients (17.7 months) had a relapse in irradiated site(s). LC
at 1, 2 and 3 years was 88%, 80.4% and 75.2%, respectively.
Most patients (834, 71.2%)
had a further distant progression. DMFS at 1, 2 and 3 years was 59.5%, 44.7%
and 40.1%, respectively. Among progressing patients, the majority (598, 71.6%)
experienced a further oligometastatic progression. In 347 patients (41.6%) the
new metastases appeared in the same organ of the irradiated lesion(s), in 341
(40.8%) in a different organ, while in 147 (17.6%) progression occurred both in
the same and in at least one different organ.
Considering both local and
distant progression, PFS at 1, 2 and 3 years was 57.2%, 43.4% and 39.4%.
During follow up, 512
(43.7%) patients died for disease progression, 55 (4.7%) died for other causes
not related to cancer. Among living patients, 159 (13.6%) remained free from
disease progression, 78 (6.7%) were still affected by active residual disease
in irradiated sites and 367 (31.3%) experienced were alive with further
metastatic disease. OS at 1,2 and 3 years was 86.6%, 65.4% and 50.3%,
respectively. KM curves are shown in figure 1.
At univariate analysis, age,
primary tumor site, disease free interval, PS, previous systemic therapies,
number of irradiated metastases, site of irradiated metastases and BED resulted
statistically significant for OS with a p value < 0,05. Primary tumor site,
disease free interval, PS, previous systemic therapies, number of irradiated
metastases, site of irradiated metastases and BED had a statistically
significant correlation with PFS.