Can The Advantages Of Video Assisted Thoracoscopic Lobectomy Be Reproduced In A Low Volume Center ?

Volume Center? Shagufta Shaheen, Salman Otoukesh, Brice Jabo, Manmeet Kaur, Nicole Wheeler, Saied Mirshahidi, Salman Zaheer, Hamid R. Mirshahidi Loma Linda University Medical Center, Loma Linda/United States of America, Loma Linda University School of Public Health, Loma Linda, CA/United States of America. 3 Loma Linda University Cancer Center, Biospecimen Laboratory, Loma Linda/United States of America -------------------------------------------------------------------------------------------------------------------


INTRODUCTION:
Surgical resection remains the mainstay of treatment in resectable lung cancers.The introduction of video assisted thoracoscopic surgery (VATS) in 1994 [1] sparked interest in minimally invasive tumor resection.VATS has also been shown to have fewer postoperative complications [2] and has been associated with decreased postoperative pain and increased quality of life compared to OT [3].Several studies have compared these two approaches indirectly, but no randomized controlled trial has investigated the long-term effect on outcomes.We sought to investigate the long-term disease-free survival and overall survival of patients with lung cancer undergoing lung resection by OT or VATS for resectable stage lung cancer.

PATIENTS AND METHODS:
Surgical Methods: VATS lung resections were performed via a three-port incision technique including a 4-centimeter anterior axillary working port.The specimens were removed via the working port.Rib spreading was not required.A hilar dissection proceeding from anterior to posterior was performed for lobectomies.For OT resections, a standard posterolateral thoracotomy was used.Generally, bulky tumors, inability to tolerate one lung ventilation, dense adhesions, en bloc chest wall resections, sleeve resections, neoadjuvant radiation therapy, or intraoperative complications were reasons for selecting an OT approach or for requiring a conversion from VATS to OT.

Study population:
Records for patients diagnosed with stage I through III resectable lung cancer treated at Loma Linda University Medical Center from May 2005 through May 2015 were retrieved through a retrospective chart review.Patients were subsequently divided into video assisted thoracoscopic surgery (VATS) and open thoracotomy (OT) groups.

Study outcomes:
Recurrence-free survival was the primary outcome and overall survival was the secondary outcome.
Survival was calculated from the date of surgery to the date of recurrence diagnosis/death or end of study follow-up (May 2016).

Study covariates:
Patient and tumor characteristics included age at diagnosis, sex, tobacco use, tumor location (side and lobe), stage, size and type of the treatments including chemotherapy or radiotherapy.

Statistical analyses:
Tumor and demographic characteristics were compared using Chis-square and Wilcoxon-Mann-Whitney tests.Purposeful variable selection approach was used to identify covariates that were included in the final models.A covariate-adjusted Cox proportional hazards model was used to compare recurrence-free and overall survival between patients treated with VATS and those treated with OT.Profile likelihood was used to estimate 95 percent confidence intervals.Proportionality was assessed using Shoenfeld residuals correlations and log-log survival plots.All tests were conducted using R software.R Core Team (2017).R: A language and environment for statistical computing.R Foundation for Statistical Computing, Vienna, Austria.URL https://www.R-project.org/.

Length of stay (LOS):
The median LOS was 2 days shorter among patients treated with VATS compared to those treated with OT [4 (3, 6) vs. 6 (4, 7), p = 0.002], Figure 3.       VATS was performed initially in the 1990's.Since then there have been multiple studies advocating the superiority of VATS over conventional OT in terms of short and long-term side effects as well as hospital length of stay [16][17][18].However, some surgeons still prefer OT over VATS.In fact, according the Society of Thoracic Surgeons General Thoracic Surgery Database, the percentage of VATS lobectomies performed in the United States are performed by VATS [19,20] at high volume centers.One explanation for this may be due to the controversial results between several comparative studies in this field [21] since during the resectable years of its development, there was a lack of a clear definition of VATS between thoracic surgeons [22][23][24].The goal of this study was to evaluate the outcomes in a low volume university setting over the last 10-year period, 2005-2015, where VATS was initiated in 2009.
Our study, like other similar articles (Table 4), did not capture any statistically significant findings between VATS and OT groups in terms of recurrence-free survival and overall survival ( p = 0.23 and p = 0.68, respectively).Also similarly, VATS lobectomy was associated with shorter length of stay and noninferior long-term survival when compared with OT lobectomy.These results support previous findings from smaller single-and multi-institutional studies that suggest that VATS does not compromise oncologic outcomes when used for resectable stage lung cancer [26].Over the last 15 years, there have been multiple studies (Table 4), which have compared VATS to OT.As noted in the table, these studies consistently showed decreased length of stay and no difference in three to five-year disease free or overall survival.Our data is consistent with other data sets retrospectively comparing VATS and OT for resection of resectable non-small cell lung cancer [8,26].
VATS lobectomy seems to have similar oncological outcomes as OT lobectomy.In VATS lobectomy the incisions are smaller and rib spreading is not performed.These patients are likely to have an overall faster recovery and may tolerate adjuvant chemotherapy better.They are also likely to have less post-operative complications and hence more likely to start and complete adjuvant chemotherapy in a timely fashion possibly leading to improved long-term outcome [15,27].
Our study has several limitations.First and most importantly, our study is a single institution retrospective study.Specific information on patient selection criteria as well as differences in surgeons' experience is lacking and may have led to selection bias.VATS, like all newly developed minimally invasive surgical techniques, requires skills and experience in which not all surgeons have been trained.

Table 1 .
Patients' characteristics by type of procedure