Clinical Characteristics of Patients with Bronchioloalveolar Carcinoma : A Retrospective Study of 44 Cases

Lung cancer is the most common cancer worldwide (Jemal et al., 2011). Bronchioloalveolar carcinoma (BAC) accounts for approximately 3-4% of all lung cancers (Read et al., 2004). In past years, BAC rose from less than 5-24.0%. A greater proportion of women and nonsmokers present with BAC than with other types of NSCLC (Barsky et al., 1994). Recently BAC recalled as adenocarcinoma in situ, minimally invasive adenocarcinoma, lepidic predominant invazive adenocarcinoma, invasive mucinous adenocarcinoma (Travis et al., 2011). Prognosis for patients with BAC better than invasive adenocarcinoma. For BAC that outcomes in localize disease are exceptional following surgical resection (Rusch et al., 2006). Although advanced stage is most common.The treatment for patients with advanced BAC are limited (Kris et al., 2006). Responsiveness to standard cytotoxic chemotherapy has been worse (Miller et al., 2005). Prospective studies of paclitaxel as therapy for advanced BAC documented modest survival (Scagliotti et al., 2005; West et al., 2005). In addition to targeted therapy have a role in treating patients with advanced disease. In patients with advanced BAC not selected on the basis of EGFR mutation was no statistically significant difference


Introduction
Lung cancer is the most common cancer worldwide (Jemal et al., 2011).Bronchioloalveolar carcinoma (BAC) accounts for approximately 3-4% of all lung cancers (Read et al., 2004).In past years, BAC rose from less than 5-24.0%.A greater proportion of women and nonsmokers present with BAC than with other types of NSCLC (Barsky et al., 1994).Recently BAC recalled as adenocarcinoma in situ, minimally invasive adenocarcinoma, lepidic predominant invazive adenocarcinoma, invasive mucinous adenocarcinoma (Travis et al., 2011).
Prognosis for patients with BAC better than invasive adenocarcinoma.For BAC that outcomes in localize disease are exceptional following surgical resection (Rusch et al., 2006).Although advanced stage is most common.The treatment for patients with advanced BAC are limited (Kris et al., 2006).Responsiveness to standard cytotoxic chemotherapy has been worse (Miller et al., 2005).Prospective studies of paclitaxel as therapy for advanced BAC documented modest survival (Scagliotti et al., 2005;West et al., 2005).In addition to targeted therapy have a role in treating patients with advanced disease.In patients with advanced BAC not selected on the basis of EGFR mutation was no statistically significant difference

Clinical Characteristics of Patients with Bronchioloalveolar Carcinoma: A Retrospective Study of 44 Cases
Nigar Dirican1 *, Aysegul Baysak2 , Gursel Cok3 , Tuncay Goksel 3 , Tulin Aysan 3 between erlotinib and chemotherapy (carboplatin plus paclitaxel) treatment for overall survival (Cadranel et al., 2011).However in presence of a somatic mutation in the epidermal growth factor receptor (EGFR) is highly associated with sensitivity to EGFR tyrosine kinase inhibitors, and for the ALK fusion oncogene, which is highly associated with sensitivity to crizotinib (Zhou et al., 2011;Rosell et al., 2012;Shaw et al., 2012).
We retrospectively evaluated the clinical features of 44 patients with BAC in the 7-year period.

Materials and Methods
This retrospective study was performed using data base including 2499 patients diagnosed as primary lung cancer.Total 44 patients with BAC were determined in the 7-year period.Patient demographics, cancer history, smoking history, other clinical features and underwent treatment were documented.Staging was performed using American Joint Committee on Cancer staging criteria (AJCC, 2010).Tumors were evaluated by an experienced pathologist, according to the 2004 World Health Organization (WHO) classification for NSCLC (Schiller et al., 2002).All specimens were formalin-fixed, paraffin-embedded, and stained with hematoxylin and eosin.The clinic parameters of those patients with BAC are shown in Table 1.

Statistical analysis
All statistical analyses were performed using SPPS version 15.0 for Windows (Statistical Package for Social Sciences, Chicago, IL).The p values <0.05 were considered statistically significant.Statistical differences between the means were analyzed by the independentsamples t-test.Survival probability was calculated using the product limit method of Kaplan and Meier, in consideration of overall deaths rate.Differences in survival between groups were determined using the logrank test.The effect of each significant predictor identified via univariate analysis was assessed via multivariate analysis using Cox's proportional hazards model.

Discussion
In this study we have retrospectively reviewed the clinical characteristics of the patients diagnosed with BAC according to the 2004 WHO classification.Despite the advantageous prognosis for patients with BAC according to other adenocarcinoma subtypes, responsiveness to standard cytotoxic chemotherapy has been worse.The Eastern Cooperative Oncology Group (ECOG) trial (E1594), median survival time of 12 months was longer than that of 8 months for the overall patients (Schiller et al., 2002).Whereas on the other retrospective analysis it was determined that median survival rate was 15 months in the advanced-stage BAC patients, median survival rate was determined as 10 months in advanced-stage NSCLC patients.Median survival rate was determined as 12 months in a prospective study made with phase II patients with infusional paclitaxel (24 h continously infused) (West et al., 2005).In the same study, the objective response rate was found as 14%, whereas 40% had stable disease.In our study, the overall response rate was 76.1%.This result is better than the aforementioned study.But in our study the median survival rate was slightly lower than the literature rates in reverse to the cytotoxic chemotherapy (median survival, 12 months).
EGFR mutations in NSCLC, KRAS mutation and ALK translocation detection is important in terms of targeted therapies.In case of detection of EGFR mutation, the use of EGFR tyrosine kinase inhibitors (erlotinib) provides a more advantageous outcome.In patients with mutant KRAS wild type dependent erlotinib treatment response is worse and survival is shorter (Brugger et al., 2011;Johnson et al., 2013).Used in the presence of ALK translocations, ALK tyrosine kinase inhibitors (crizotinib) significantly prolongs survival rate (Shaw et al., 2012).
TNM staging in the NSCLC is the most influential factor on prognosis.According to the Surveillance, Epidemiology and End Results (SEER) database the median survival time of 60 months was reported for clinical stage I patients, and the median survival time was reported to be 6 months for the clinical stage IV patients (Groome et al., 2007).According to our data median overall survival rate of all patients was 12 months.Also according to the TNM stage in pN was found to be an independent risk factor (HR: 3.81,p=0.018).Similiar to our study, previously conducted similar studies also showed the number of positive lymph nodes (Fukui et al., 2006;Lee et al., 2008;Bria et al., 2009) as strong independent prognostic factor in NSCLC patients.
Poor performance status (PS) is defined by one of the other poor prognostic risk factors.Lower performance statuswas defined as one of the worst 6 risk factors for NSCLC (ECOG 1 or 2; HR, 1.46) (Hoang et al., 2005).In another study, a statistically significant difference was found in NSCLC patients with WHO PS=0 and PS=1 in the median survival rate (51.5 months versus 15.4 months, respectively, p<0.0001) (Kawaguchi et al., 2010).Our results also showed a significant correlation between poor performance status and prognosis (KPS <80 vs KPS ≥80, HR 3.30, p=0.009).The effect of Hemoptysis on the prognosis of lung cancer could not have been clearly identified.In one study, lung cancer was found to have a particularly strong relationship with hospital mortality (Lee et al., 2012).In our study, the risk of death was higher in patients with hemoptysis (HR: 2.31, p=0.046).No statistically significant relationship was found between the other symptoms, smoking status and the number of metastases and the prognosis.
In conclusion, the most important factors limiting this study are the retrospective, single-center experience and the small number of patients.According to the results of this study cytotoxic chemotherapy does not seem very efficient in BAC.According to the results of our study and previous studies, targeted therapies individualized according to the molecular specificationsshould be kept at the forefront before the cytotoxic chemotherapy.Also in our study, TNM stage, positive lymph nodes, poor performance status, and hemoptisis were found to be independent prognostic risk factors.

Table 1 . Patient Characteristics
Figure 1.Overall Survival in all Patients

Table 2 . Univariate Survival Analysis for Overall Survival
*pack years, ±Karnofsky performance status (KPS)