Author's response to reviews

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1 Author's response to reviews Title: Brain metastasis development and poor survival associated with carcinoembryonic antigen (CEA) level in advanced non-small cell lung cancer: a prospective analysis Authors: Oscar Arrieta (ogar@servidor.unam.mx) David Saavedra (seelowen@msn.com) Roberto Kuri (cuitlacoche74@hotmail.com) Alejandro Aviles-Salas (alejandroaviles2001@yahoo.com) Luis Martinez (luismartinbarr@yahoo.com.mx) Daniel Mendoza-Posada (danielm3742@gmail.com) Patricia Castillo (patycastillog@hotmail.com) Alma Astorga (alma_astorga@yahoo.es) Enrique Guzman (enriqueg@prodigy.net.mx) Jaime De la Garza (jdelagarza1@prodigy.net.mx) Version: 2 Date: 4 March 2009 Author's response to reviews: see over

2 Tuesday, March 3, Melissa Norton, M.D. Editor-in-Chief BMC Cancer Editorial Office Review SECOND VERSION: manuscript Title: Brain metastasis development and poor survival associated with carcinoembryonic antigen (CEA) level in advanced non-small cell lung cancer: a prospective analysis Dear Dr. Norton: We appreciate the comments made to our manuscript; undoubtedly they have increased the quality of our paper. Enclosed please find the revised manuscript and a detailed description point by point attending the reviewers comments. All authors have read and approved this version of the manuscript, and concur with the submission. Waiting your reply, I remain. Yours sincerely, Oscar Arrieta M.D. Department of Medical Oncology, Instituto Nacional de Cancerologia. San Fernando No. 22, Col. Seccion XVI, Tlalpan, 14080, Mexico City, Mexico. Telephone: (+52) ext 832; Fax (+52) ; ogar@servidor.unam.mx

3 REVIEWER 1 (Katsunari Matsuoka): Comments: There are many reports which demonstrated the relationship between serum CEA level and overall survival or postoperative recurrence, but this report focused on the relationship between serum CEA level and brain metastasis. Although the aim of this study is good, I have some questions in this article. 1) Although 293 patients enter this study, EGFR and HER2 expression was analyzed with the biopsy specimen of only 85 patients. Is there any patients selection bias at EGFRs sampling? There was no selection bias for the EGFRs-immunohistochemical study. Most patients are referred to our Institute without paraffin blocks and in others the diagnosis was based on cytopathological samples; even when tissue samples were available, some of them were insufficient to perform the immunohistochemistry. Moreover, all patients were consecutively enrolled, thus we think that there is no selection bias. This information has been added to the Results section of revised manuscript (Page 10, Paragraph 1, Lines 1 and 7-10). 2) As serum CEA level had no correlation with the expression of EGFRs and EGFRs expression was not significant in terms of CNS metastasis development, were the results of EGFRs needed in this article? As mentioned in the Background section, EGFR has a high biological importance in patients with non-small cell lung cancer (NSCLC), and HER2-positive tissue expression is a recognized risk factor for brain metastasis (BM) development in breast cancer; therefore, our initial hypothesis included these two biomarkers and high CEA serum levels as possible risks factors for BM development. However, EGFR-positive expression showed no relationship with BM development, and due to low frequency of HER2-positive patients, we could not make any conclusion about the role of this biomarker in the BM development of patients with NSCLC. As suggested by both reviewers, the Discussion section about EGFRs has been reduced in the revised manuscript. 3) Serum high CEA level had significant correlation with the histological type, adenocarcinoma. I would like to know the results of subgroup analysis about the patients with adenocarcinoma. We performed an analysis of association between basal CEA serum levels and CNS metastasis development exclusively in patients with adenocarcinoma, founding a more notorious difference concerning the CNS metastasis development than in our complete cohort. Frequency

4 + standard error of CNS metastasis development at 12 months of diagnosis were % (95% CI, %) and % (95% CI, ), in patients with CEA serum levels < 40 ng/ml, and > 40 ng/ml, respectively. And at 24 months of diagnosis, frequency + standard error of CNS metastasis development were % (95% CI, %) and % (95% CI, %) in patients with CEA serum levels < 40 ng/ml and levels > 40 ng/ml, respectively. This information has been added to Results section of the revised manuscript (Page 11, Paragraph 1, Lines 7-14). 4) It is difficult to understand the Table 3. Table 3 should be rewritten. Table 3 was deleted from the revised manuscript. The results contained in this table are explained in the Results section (Page 10, Paragraph 2, Lines 3 to the end of paragraph): Age, gender, positive smoking history, status performance, histological-grade of differentiation and presence of liver metastasis at diagnosis were not associated to the CEA serum levels elevation. However, at the uni- and multivariate analysis, factors associated with basal CEA serum levels > 40 ng/ml were adenocarcinoma histological type (frequency of 41.3% compared with 14.1% of patients with other histology, including squamous or large-cell histologies, RR 1.6; 95% CI, ; p = 0.005) and presence of CNS metastasis at diagnosis (frequency of 77.7% compared with 12.3% of patients without CNS metastasis at diagnosis, RR 14.05; 95% CI, ; p <0.001). 5) In the first paragraph of CNS metastasis in Results, what is (23-30) and (21-43)? What number is it? The numbers (23-30) and (21-43) represents the estimated 95% confidence interval for BM development at 1 and 2 years of diagnosis in our cohort, respectively. We added the abbreviation 95% CI to each interval for its meaning specification (Page 11, Paragraph 1, Lines 1 and 2). 6) Table legends of Table 1 and Table 2 were confused. Legend of Table 1 was rewritten (Page 25, Table 1 section). Table 2 was deleted from the manuscript and all shown results were included in the Results section (Page 10, Paragraph 2, Lines 1 3): In 42.8, 32.3, 22.2, and 21.4% of patients, basal serum CEA level was >10, 20, 40, and 50 ng/ml at diagnosis, respectively (median + standard deviation, ,021 ng/ml; range, ,475 ng/ml).

5 REVIEWER 2 (Akinori Iwasaki): Comments: I have some comments about this paper: 1) Author evaluated two different factor (serum level of CEA and tissue expression of EGFR, or HER2) in this study. Author consider exclusive the data EGFR, or HER2 because of few discussion sentence focused on these factor survival rate. And it is not clear to me why present the EGFR/HER2 study. EGFR has a high biological importance in patients with non-small cell lung cancer (NSCLC), and HER2-positive tissue expression is a recognized risk factor for brain metastasis (BM) development in breast cancer; therefore, our initial hypothesis included these two biomarkers and high CEA serum levels as possible risks factors for BM development. However, EGFR-positive expression showed no relationship with BM development, and due to low frequency of HER2- positive patients, we could not conclude about the role of this biomarker in the BM development of patients with NSCLC. As suggested by both reviewers, the Discussion section about EGFRs has been reduced in the revised manuscript. 2) It is not clear how cut-off level (>40ng/mL) in this study. Table 2 showed the cut-off points according to normal CEA and serum level previously reported (<10ng/dL). Author should be more clear. We found differences between CNS metastasis presence at diagnosis and overall survival rates in our cohort patients, according to cut-off CEA serum levels > 10, y 40 ng/ml; however, related differences to both variables were more notorious with a cut-off point of CEA serum level > 40 ng/ml, thus we selected this value to perform our subsequent analyses. This information was added to the Discussion section (Page 15, Paragraph 2). 3) Table 3: it is better a word Well from Good. As suggested by Reviewer 1, Table 3 was deleted from the revised manuscript. The results contained in this table are explained in the Results section (Page 10, Paragraph 2, Lines 3 to the end of paragraph): Age, gender, positive smoking history, status performance, histological-grade of differentiation and presence of liver metastasis at diagnosis were not associated to the CEA serum levels elevation. However, at the uni- and multivariate analysis, factors associated with basal CEA serum levels > 40 ng/ml were

6 adenocarcinoma histological type (frequency of 41.3% compared with 14.1% of patients with other histology, including squamous or largecell histologies, RR 1.6; 95% CI, ; p = 0.005) and presence of CNS metastasis at diagnosis (frequency of 77.7% compared with 12.3% of patients without CNS metastasis at diagnosis, RR 14.05; 95% CI, ; p <0.001). 4) Discussion is rather lengthy and boredom, and might easily be reduced to one third of its current extent. I would recommend you the reduced of the Five Tables( too many). As suggested by both reviewers, the Discussion section about EGFRs has been reduced in the revised manuscript and total number of tables are now 3 (Table 2 and 3 were deleted). 5) Gamma knife, brain irradiation or surgery to the brain must be clear, because it might be influenced the outcome of survival. As treatment for brain metastasis, only 4 patients achieved criteria to undergo radiosurgery, none of the patients was submitted to brain surgery, and all other patients received whole brain irradiation. This information has been added to Results section of the revised manuscript (Page 11, Paragraph 1, Lines 2-4). 6) I think it might be relation brain metastasis and N2 status( location, numbers, N1 and N2, skip metastasis), T factors (tumor size, dissemination, etc ). All enrolled patients were diagnosed as advanced disease (clinical stages IV or IIIB with pleural effusion), thus, they did not have a mediastinum-status evaluation (mediastinoscopy) because standard treatment schedules are based only on chemotherapy. Moreover, due to the nature of advanced disease, N2 status may be present in nearly all patients, as part of the metastatic process sequence. Hence, analysis of lymph-node metastasis and T factors can be more interesting in early than in advanced disease. 7) My major concern with this paper is that the basis for tumor marker. Did analyse another marker such as cytokeratin (CYFRA), SCC, pro- GRP,NSE, etc The aim of this study was to evaluate exclusively CEA serum levels, EGFR and HER2-tissue expression as biomarkers for brain metastasis development in patients with NSCLC. Although, there are other types of cell-adhesion molecules associated to lymph-node metastasis development (as chemokine receptors CCR7, CXCR3 and CCL21 [50, 51]) and they could be related with brain metastasis development too, analysis to evaluate their association to brain metastasis development in NSCLC patients should be the objective of other studies.

7 This information has been added to Discussion section (Page 14, Paragraph 1, Lines 16-19, References 50 and 51). All changes are underlined in the revised manuscript.