Lung Cancer

PV QA 4 - Poster Viewing Q&A 4

TU_25_3565 - Patterns of Failure for Patients Treated for Synchronous Primaries with SBRT

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Patterns of Failure for Patients Treated for Synchronous Primaries with SBRT
B. Altoos Jr1, C. Small2, K. Stang3, C. J. Miller Jr2, R. Hutten1, F. Alite Jr2, and M. M. Harkenrider2; 1Stritch School of Medicine, Loyola University Chicago, Maywood, IL, 2Department of Radiation Oncology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, 3Department of Radiation Oncology, Loyola University Medical Center, Maywood, IL

Purpose/Objective(s): SBRT to synchronous lung primaries is considered generally safe with local control comparable to SBRT to a single focus of disease. Although treatment is safe, hesitation among radiation oncologists exists in treating synchronous lesions with SBRT given concern that synchronous lesions represent metastatic disease and warrant a different treatment paradigm. Therefore, we aimed to assess patterns of failure in these patients.

Materials/Methods: We performed an analysis of our retrospective SBRT database with patients treated between 2006-2015 with LINAC based lung SBRT to identify patients treated for synchronous primaries. Study design and development were approved by institutional review and privacy boards. Local control, regional failure, and distal failure were calculated from date of first fraction of SBRT to last follow up.

Results: We identified 20 patients (43 tumors) that were treated synchronously with SBRT. 50 or 60Gy in 5 fractions were the most commonly employed regimens. The median age of patients examined was 79 years of age (IQR 74-81), median KPS was 90 (70-90), and medium tumor size was 2 cm (IQR 1.3 – 2.9). After a median follow up of 17 months, 80% of patients achieved local control (93% of tumors), 85% achieved regional control, and 30% developed distant metastasis. The median time for regional recurrence and distant metastasis was 24 months (IQR 21-25.5 months) and 10 months (IQR 6-21 months), respectively. The majority of patients (55%) had tumors of bilateral lungs, 25% had tumors in ipsilateral lung but not within the same lobe, and 20% of patients had tumors within the same lobe. Patients with contralateral tumors had non-significantly higher rates of locoregional relapse (27% versus 11, p=0.38) and significantly higher rate of distant metastasis (36% versus 22%, p=0.05). Only one patient developed grade 2 pneumonitis and one patient developed a grade 2 pericardial effusion. No grade 3-5 pneumonitis were reported.

Conclusion: Expectedly, local control for treated tumors was excellent. Taken together, rates of regional control and time to progression regionally is similar to historical controls; although, rates of distant metastases was higher than historical series and time to distant metastasis was short. Patients with synchronous primaries with contralateral lung lesions had comparably higher rates of distant disease and thus may identify a high risk population that may benefit from addition of systemic therapy.

Author Disclosure: B. Altoos: None. C. Small: None. C.J. Miller: None. M.M. Harkenrider: Radiation oncology program director and Trustee; Chicago Radiological Society.

Basel Altoos, MD

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