Chemotherapy-induced neutropenia as a prognostic factor in advanced non-small-cell lung cancer: results from Japan Multinational Trial Organization LC00-03.

BACKGROUND: Neutropenia is a common adverse reaction of chemotherapy. We assessed whether chemotherapy-induced neutropenia could be a predictor of survival for patients with non-small-cell lung cancer (NSCLC). METHODS: A total of 387 chemotherapy-naïve patients who received chemotherapy (vinorelbine and gemcitabine followed by docetaxel, or paclitaxel and carboplatin) in a randomised controlled trial were evaluated. The proportional-hazards regression model was used to examine the effects of chemotherapy-induced neutropenia and tumour response on overall survival. Landmark analysis was used to lessen the bias of more severe neutropenia resulting from more treatment cycles allowed by longer survival, whereby patients who died within 126 days of starting chemotherapy were excluded. RESULTS: The adjusted hazard ratios for patients with grade-1 to 2 neutropenia or grade-3 to 4 neutropenia compared with no neutropenia were 0.59 (95% confidence interval (CI), 0.36-0.97) and 0.71 (95% CI, 0.49-1.03), respectively. The hazard ratios did not differ significantly between the patients who developed neutropenia with stable disease (SD), and those who lacked neutropenia with partial response (PR). CONCLUSION: Chemotherapy-induced neutropenia is a predictor of better survival for patients with advanced NSCLC. Prospective randomised trials of early-dose increases guided by chemotherapy-induced toxicities are warranted.

Immunoregulatory T-lymphocyte functions in patients with small cell lung cancer.

The present study was performed to elucidate the differences in immune status between patients with small cell lung cancer (SCLC) and those with non-small cell lung cancer. The study group consisted of 18 patients with SCLC and 15 with non-SCLC. Two healthy volunteers and 13 patients with benign disease were also included in the present study as the non-cancer control. In the non-SCLC group, although not statistically significant, the percentages of both OKT3+ and OKT4+ T-lymphocytes in the peripheral blood lymphocytes (PBL) were slightly decreased, associated with a slight increase in the percentage of OKT8+ T-cells, and a slight decrease in the OKT4+ to OKT8+ T-cell ratio. In contrast, the PBL of the SCLC patients showed significantly lower proliferative responses to phytohemagglutinin and human recombinant interleukin 2 than did the PBL of both the SCLC patients and the noncancer control group. The ability of PBL to produce lymphokines (interleukin 2 and macrophage activating factor) was significantly impaired in the SCLC group but not in the non-SCLC group. These results suggest that suppression of helper T-cell functions and/or potentiation of suppressor T-cell functions should occur in patients with SCLC.

Murine tumor cell lysis by antibody-dependent macrophage-mediated cytotoxicity using syngeneic monoclonal antibodies.

Four monoclonal antibodies to MH134 murine syngeneic hepatoma cells, 3H1, 7C2, 11G2, and 12A2, were produced by hybridomas constructed by fusing P3-X63-Ag8-U1 murine myeloma cells with spleen cells of a C3H/HeN mouse immunized with the syngeneic tumor cells. Immunodiffusion analysis with rabbit anti-mouse immunoglobulin antisera showed that 3H1, 7C2, 11G2, and 12A2 are IgG2a, IgM, IgG1, and IgG2a, respectively. Enzyme-linked immunosorbent assay using cells of five syngeneic tumor lines, MH134, MM102, MM46, MM48, and X5563, and lymph node cells of C3H/HeN and C57BL/6 mice showed that 3H1 specifically bound to MH134 tumor cells, whereas 7C2, 11G2, and 12A2 reacted not only with MH134 but also with MM102 and MM46 tumor cells. None of these monoclonal antibodies bound either to cells of MM48 or X5563 tumor lines or to normal lymph node cells. These results strongly suggest that MH134 tumor cells display at least two kinds of tumor-associated antigens on their cell surfaces: one is expressed uniquely by MH134 tumor cells, which are recognized by 3H1; the other is commonly shared by MH134, MM102, and MM46 tumor cells, which are determined by the other three antibodies. 3H1, 11G2, and 12A2 but not 7C2 were found to be able to induce antibody-dependent cellular cytotoxicity (ADCC) against MH134 tumor cells. Target specificity of ADCC induced by these monoclonal antibodies was identical with that seen in enzyme-linked immunosorbent assay. 3H1, 7C2, and 12A2 but not 11G2 exhibited complement-dependent cytotoxicity, showing the same specificity in target cell lysis as that seen in enzyme-linked immunosorbent assay or ADCC. Pretreatment of MH134 tumor cells with 7C2 inhibited ADCC of both 11G2 and 12A2. Pretreatment of the tumor cells with 11G2 inhibited complement-dependent cytotoxicity of both 7C2 and 12A2. Neither ADCC nor complement-dependent cytotoxicity of 3H1 was inhibited by the pretreatment of the cells with 7C2 or 11G2. These results strongly suggest that tumor-associated antigens recognized by 3H1 are located apart from that recognized by 7C2, 11G2, and 12A2 and that the binding sites of the latter three antibodies are closely associated with, or identical with, each other in the tumor-associated antigen. The ability of 12A2 to induce ADCC against MH134 tumor cells was significantly stronger than that of 3H1 or 11G2.(ABSTRACT TRUNCATED AT 400 WORDS)

Macrophage tumoricidal activity as a possible antitumor mechanism associated with the local injection of allogeneic spleen cells into rats.

The in vivo antitumor effect of i.p. injection of allogeneic spleen cells was investigated. ACl rats were inoculated i.p. with 10(4) AMC-60 syngeneic fibrosarcoma cells and given injections i.p. of 4 X 10(7) Wistar spleen cells once a week for 3 wk from 1 day after tumor inoculation. This treatment significantly prolonged the survival period of the tumor-bearing rats. A similar effect was obtained by i.p. injections of Lewis spleen cells. Injection i.p. into ACl rats of spleen cells of these rat strains resulted in the apparent augmentation of cytolytic activity of peritoneal adherent but not of nonadherent cells against AMC-60 tumor cells. The cytotoxicity was exhibited nonspecifically to cells of a variety of tumor lines but not to concanavalin A blasts of ACl spleen cells and was inhibited by the addition of carrageenan. Irradiation (2000 R) of Lewis spleen cells or fractionation of the allogeneic spleen cells using nylon wool columns revealed that a radiosensitive and nylon wool-passed cell population, presumably a T-cell population, of the allogeneic spleen cells is responsible for the augmentation of peritoneal macrophage tumoricidal activity in ACl rats. Further, Lewis spleen cells irradiated at 2000 R neither augmented peritoneal macrophage cytotoxicity nor prolonged the survival period of ACl rats bearing AMC-60 tumor, suggesting that the augmentation of peritoneal macrophage cytotoxicity plays a major role in the in vivo antitumor effect of the allogeneic spleen cell transfer. ACl rats were given injections i.p. of 4 X 10(7) Lewis spleen cells. Two days after injection, cells including peritoneal cells of the ACl rats and Lewis spleen cells remaining in the peritoneal cavities were obtained by peritoneal lavages and then incubated for 5 days. Significant blastogenic proliferation was observed, and the supernatant of the culture was shown to be able to render thioglycollate-induced peritoneal macrophages of ACl rats cytotoxic to AMC-60 tumor cells, indicating that a certain cell population of the cell mixture produced a lymphokine(s) resembling macrophage activating factor (MAF) during the incubation. When ACl rats were given injections i.p. of irradiated Lewis spleen cells, neither the blastogenic proliferation nor the generation of MAF activity in the culture supernatant was observed. Indirect immunofluorescence analysis using rabbit anti-ACl and anti-Lewis antisera revealed that as many irradiated Lewis spleen cells were remaining in the peritoneal cavities as normal Lewis spleen cells 2 days after injection into ACl rats.(ABSTRACT TRUNCATED AT 400 WORDS)

Combined therapy of mice bearing a lymphokine-activated killer-resistant tumor with recombinant interleukin 2 and an antitumor monoclonal antibody capable of inducing antibody-dependent cellular cytotoxicity.

The ability of lymphokine-activated killer (LAK) cells to mediate antibody-dependent cellular cytotoxicity and its efficacy against a LAK-resistant tumor were investigated. Cells of the MH134 murine hepatoma line are scarcely lysed by LAK cells generated in vitro by incubation of C3H/HeN mouse spleen cells with human recombinant interleukin 2 (rIL 2). However, the splenic LAK cells potently lysed the LAK-resistant tumor cells in the presence of 11G2, a monoclonal antibody (MAb) of the IgG1 isotype reactive with a part of MM antigen. Peritoneal cells induced by daily i.p. injections of rIL 2 not only exhibited LAK activity but also mediated antibody-dependent cellular cytotoxicity against MH134 tumor cells in the presence of 11G2. The peritoneal cells exhibiting these cytotoxic activities were found to be nonadherent and nonphagocytic mononuclear cells possessing a similar cell surface phenotype as that of splenic LAK cells, that is Thy-1.2+ approximately -, Lyt-1.1-, Lyt-2.1-, and asialo GM1+. Treatment of spleen cells with antibodies and complement before culture with rIL 2 revealed that the phenotype of splenic LAK precursors is Thy-1.2- and asialo GM1+. The in vivo induction of peritoneal LAK cells in response to i.p. injections of rIL 2 was markedly depressed in C57BL/6 beige mice but was normally accomplished in BALB/c nude mice. Combined therapy of C3H/HeN mice bearing MH134 ascitic tumor with i.p. injection of rIL 2 and 11G2 brought about potent suppression of the tumor growth, resulting in the significant increase in the number of tumor-free mice, whereas neither rIL 2 nor the MAb could exhibit such a potent antitumor effect when used alone. Injection (i.v.) of anti-asialo GM1 antibody not only blocked the induction of peritoneal LAK cells by rIL 2 but also abrogated the development of the antitumor effect of the combined therapy. These results strongly suggest that combination of antitumor MAbs capable of inducing antibody-dependent cellular cytotoxicity with rIL 2 therapy could result in the generation of potent antitumor effects against LAK-resistant tumors and that asialo GM1-positive non-T-cell populations including cells of the natural killer cell lineage are essential, at least in part, for development of the antitumor effects of the combined therapy with rIL 2 and MAbs.

Irinotecan and etoposide for previously untreated extensive-disease small cell lung cancer: a phase II trial of West Japan Thoracic Oncology Group.

Irinotecan is a topoisomerase I inhibitor that is highly active against small cell lung cancer (SCLC). Etoposide is another drug that is effective for SCLC. Since combination of these two topoisomerase inhibitors revealed a synergistic effect in vitro and showed a safety in phase I study, we conducted a phase II study in patients with previously un-treated extensive disease (ED) SCLC to evaluate the efficacy and toxicity of this combination. Fifty patients with previously untreated ED-SCLC were enrolled. Irinotecan was administered intravenously at 60mg/m(2) on days 1, 8, and 15, while etoposide was given at 80mg/m(2) on days 2-4. Treatment was repeated every 4 weeks for four cycles. The overall response rate was 66.0%, with a complete response rate of 10.0%. The median survival time was 11.5 months and the 1- and 2-year survival rates were 43.2 and 14.4%, respectively. The major toxicity of this regimen was myelosuppression, including grade 3 or 4 neutropenia (62.9%), leukopenia (28.0%), and anemia (14%). The other grade 3 toxicity was diarrhea (2%). This irinotecan and etoposide regimen is active against ED-SCLC with relatively mild toxicity.

Frequency of apoptosis of tumor-infiltrating lymphocytes induced by fas counterattack in human colorectal carcinoma and its correlation with prognosis.

We investigated apoptosis in tumor-infiltrating lymphocytes (TILs) obtained from 41 colorectal carcinomas by in situ nick translation (ISNT). When the ISNT labeling index (LI) was determined as the number of positive nuclei per 1000 nuclei of TIL in tissue sections, the median LI was 12.0 (range, 2-30). The ISNT LI of colorectal carcinoma with lymph node metastasis was higher than that of colorectal carcinoma without metastasis. The cases with a high LI of 212.0 had a significantly poorer prognosis than those with a low LI. We also confirmed immunohistochemically that a part of the TILs expressed Fas using the sections adjacent to what contained abundant ISNT-positive TILs. Moreover, Fas ligand (FasL) expression was detected on the cell surface as well as the cytoplasm of colorectal cancer cells in 61% of cases. Apoptosis in TILs was consistently seen more frequently in FasL-positive cases than in FasL-negative ones. These findings indicate that the FasL expressed in colorectal carcinoma cells may kill the Fas-positive immune effective TILs by means of a Fas-FasL system termed Fas counterattack. This tumor immune evasion induced by FasL may therefore affect the malignant potential of human colorectal carcinoma.

Localization of cyclic adenosine 3',5'-monophosphate-responsive element (CRE)-binding proteins by southwestern histochemistry.

Regulation of gene transcription requires an interaction between specific segments of nuclear DNA and specific proteins. We describe a method to localize the specific DNA-binding proteins using haptenized double-stranded (ds) DNAs. To demonstrate this method, an oligodeoxynucleotide (oligo-DNA) with a consensus base sequence of cyclic adenosine monophosphate-responsive element (CRE) (TGACGTCA) with three TTA repeats at the 5' end was synthesized. Since the CRE sequence is palindromic, the oligo-DNA was allowed to self-anneal and form ds DNA with three TTA repeats at both ends. The CRE ds-oligo-DNA was irradiated with UV light to form haptenic thymine-thymine (T-T) dimers. The haptenized CRE ds-oligo-DNA reacted by Southwestern analysis with a distinct set of proteins, previously identified as CRE-binding proteins, ranging from 40-90 KD. When the haptenized CRE ds-oligo-DNA reacted with frozen sections fixed with 4% paraformaldehyde in PBS (pH 7.4) followed by enzyme immunohistochemical localization of the T-T dimers, nuclei of intestinal epithelial cells and brain cells were heavily stained. Nuclear staining was blocked when the sections were reacted with the haptenized CRE ds-oligo-DNA in the presence of an excess amount of non-haptenized CRE ds-oligo-DNA. This method, henceforth referred as Southwestern histochemistry, should be a useful tool to localize proteins that bind to a specific DNA sequence and regulate the transcriptional activity of genes.

Slow N-acetyltransferase 2 genotype affects the incidence of isoniazid and rifampicin-induced hepatotoxicity.

SETTING: Japanese in-patients with pulmonary tuberculosis and normal liver function receiving treatment with isoniazid and rifampicin (INH + RMP). OBJECTIVE: To elucidate the relationship between N-acetyltransferase 2 (NAT2) genotype and the incidence of isoniazid + rifampicin-induced hepatotoxicity. DESIGN: Prospective study. After NAT2* genotyping, 77 patients were classified into three groups according to their NAT2* genotypes: rapid-type (a homozygote of NAT2*4), intermediate-type (a heterozygote of NAT2*4 and mutant alleles) and slow-type (a combination of mutant alleles). Their biochemical profiles of liver function test were investigated for 3 months to assess the development of serum aminotransferase elevation. RESULT: Of the 77 patients, 18.2% developed adverse hepatic reaction within the first month of INH + RMP treatment. A significant association was observed between hepatotoxicity and NAT2* genotype: compared with rapid-type, the relative risk was 4.0 (95% CI 1.94-6.06) for intermediate-type and 28.0 (95%CI 26.0-30.0) for slow-type. Especially in slow-type, the incidence of hepatotoxicity and serum aminotransferase elevation was significantly higher than in the other two types. CONCLUSION: Slow NAT2* genotype significantly affected the development of INH + RMP-induced hepatotoxicity. This suggests the possibility that NAT2* genotyping prior to medication may be useful in evaluating patients with high risk for INH + RMP-induced hepatotoxicity.

MRI facilitated a diagnosis of endometriosis of the rectum.

A 51-year-old pre-menopausal Japanese woman suffering from chronic lower abdominal pain was referred to our hospital. A barium enema showed a stenotic lesion in the recto-sigmoid region, and a pelvic computed axial tomography (CAT) scan revealed a thickened rectal wall. A colonoscopic examination showed the rectum to be constrictive, but the mucosa appeared to be intact. Magnetic resonance imaging (MRI) with T1 high-intensity revealed a cystic lesion in the thickened wall of the rectum, which led us to suspect possible bowel endometriosis. Part of the biopsy specimen showed endometrial epithelium within the interstitial layer of histologically normal mucosa; finally, endometriosis of the rectum was diagnosed. The patient became asymptomatic after the initiation of hormonal treatment and later experienced spontaneous menopause. MRI was effective for diagnosis and the patient did not undergo unnecessary laparotomy. Although bowel endometriosis is generally diagnosed by means of resected specimens, in our patient, diagnosis was made using MRI and biopsy, and hormonal therapy had an effective role as a bridge to menopause.

Human colon cancer produces a factor which induces the proliferation of venous endothelial cells.

This study was performed to investigate whether colorectal cancers produce proliferative factors for venous endothelial cells, and whether the proliferative activity is related to basic FGF and VEGF and also to the clinicopathological findings. Surgically resected specimens of 17 colorectal cancer patients were fragmented and cultured, and the supernatant was collected. A human umbilical endothelial cell line (EA-hy 926 cells) was incubated with the supernatant. The proliferative activity was examined and the levels of basic FGF and VEGF were measured. The activities were found to be significantly related to VEGF, the depth of tumor invasion and the tumor stage.

Expression of epidermal growth factor receptor messenger RNA in human colorectal carcinomas assessed by non-radioactive in-situ hybridization.

No consensus as to the involvement of the epidermal growth factor receptor (EGF-R) in colorectal carcinomas has yet been attained, although they are assumed to play a role in the metastasis to lymph nodes and recurrence of breast carcinoma and bladder carcinoma invasion. Knowing that Dukes' classification of colorectal carcinoma is closely related to prognosis, we examined whether there is a correlation between Dukes' classification and the expression of EGF-R in colorectal carcinoma. If there is a positive correlation, the involvement of EGF-R in the processes may be assumed and the expression of EGF-R may be used as a marker of their prognosis. To this end, the expression of EGF-R mRNA and protein by non-radioactive in-situ hybridization and immunohistochemistry, respectively, were determined on histological preparations of formalin-fixed paraffin-embedded colorectal surgical specimens. In 30 cases of colorectal carcinoma examined, mRNA and/or protein was detected in 33% (two of six) of Dukes' A, in 40% (four of 10) of Dukes' B, in 36% (four of 11) of Dukes' C, in 33% (one of three) of Dukes' D and in 0% of normal colon epithelial cells. Thus, there was no positive correlation between the Dukes' classification and the expression of EGF-R. It is concluded that the expression of EGF-R in colorectal carcinoma is not a promising marker of prognosis. However, the role of EGF-R in EGF-R positive tumours remains to be examined.

The detection of colorectal cancer at an asymptomatic stage by screening is useful.

BACKGROUND/AIMS: The validity of mass screening using fecal occult blood testing remains controversial. In addition, no controlled clinical study has yet been performed to show the usefulness of sigmoidoscopy. The purpose of the present study was to compare the surgical results achieved in asymptomatic patients with colorectal cancer detected by screening with those in symptomatic individuals. METHODOLOGY: A total of 285 patients underwent a surgical resection of colorectal cancer between 1991 and 1997 at our institution. Among them, 233 patients had complaints related to cancer at the time of diagnosis. In contrast, 52 were asymptomatic. In those 52 patients, colorectal cancer had been suspected based on routine screening including fecal occult blood testing, colonoscopy and/or elevated serum levels of carcinoembryonic antigen. RESULTS: Early stage of colorectal cancer was more frequently seen in asymptomatic patients than in symptomatic patients P < 0.01. The survival rates for asymptomatic patients was also superior to those of symptomatic patients P < 0.05. CONCLUSIONS: Screening using fecal occult blood testing, colonoscopy and tumor markers is thus considered to be beneficial for the early detection of colorectal carcinoma, which also tends to demonstrate good surgical results.

[Improvement in quality of life with vinorelbine as a single agent in two patients with recurrent lung cancer].

Two patients with lung cancer that recurred after surgery and chemotherapy were administered vinorelbine (20 mg/m2) as a single agent on days 1 and 8 every 4 weeks. Patient 1 had recurrences in both lung lobes and metastases in the bone and liver after surgery, while patient 2 had a recurrence in the left lung lobe and metastases in the brain and liver after prior chemotherapy. In both patients, vinorelbine treatment improved several clinical indicators of cancer symptomatology including serum LDH, levels of other clinical blood tests, as well as a subjective assessment of the quality of life (QOL). Both patients were discharged from the hospital and subsequently treated on an outpatient basis. Because recurrent lung cancer patients generally have a poor performance status, chemotherapy for these patients is thought to worsen the QOL and increase hospital stays. The present report suggests that vinorelbine, as a single agent, might improve the QOL and make it possible to treat recurrent lung cancer patients on an outpatient basis.

[Pulmonary granulomatous lesion with severe chest pain and hemoptysis: a case report].

We encountered a rare case of pulmonary granulomatous lesion accompanied with severe chest pain and hemoptysis. A 42-year-old man visited our hospital complaining of hemosputum. A chest radiograph showed a nodular shadow in the left lower lung field. Further examinations including fiberoptic bronchoscopy, bronchoalveolar lavage and transbronchial lung biopsy did not suggest a diagnosis. During the course of his illness, he suffered an episode of severe chest pain which could be controlled only by intravenous morphine chloride (10 mg). The chest radiograph at the time showed a broad infiltration in the left lower lung field. However, the lung perfusion scintigram taken 2 days before demonstrated decreased blood flow in the same field. We waited for the infiltration in the chest radiograph to diminish and then performed partial resection of the left lower lobe, thus terminating both hemosputum and chest pain. Histological examination showed a cavitary lesion in the periphery of the lung, surrounded by large numbers of infiltrating plasma cells and lymphocytes, among which were many hemosiderinladen macrophages. A small amount of mycelium, considered to be Nocardia or fungus, was seen in the cavity wall. These findings may indicate that an infection had contributed to the formation of a hemorrhagic granulomatous lesion, and that this lesion caused chest pain mainly because of the pleuritis and the decrease in the local pulmonary circulation.

[Metastasis of small cell lung cancer to the parotid gland as the initial clinical manifestation, followed by metastases to the pituitary gland and lumber spinal cord].

The patient was a 48-year-old woman. In January 1995, she noted swelling in the left parotid gland, and saw an otorhinolaryngologist. Needle biopsy showed small cell carcinoma, and she was subsequently admitted to our hospital. Chest radiography revealed a tumor shadow in the hilus of the right lung. Bronchial biopsy revealed small cell carcinoma of the lung (T 4 N 3 M 1, stage IV). Chemotherapy, with a CDDP-VP-16 regimen, achieved no response. She later developed bitemporal hemianopsia and abducens nerve palsy. Brain MRI revealed metastasis in the pituitary gland. Chemotherapy and radiotherapy were efficacious for only a few months. She also developed pain and numbness in the left leg, attributable to intramedullary metastasis (L 1/2, L 4/5) shown on MRI. It is extremely rare for a metastasis to the parotid gland to be the initial clinical manifestation of a small cell lung cancer which later develops widespread metastases to the pituitary gland and lumbar spinal cord.

[Evaluation of immunoreactivity to erbB-2 protein as a marker of prognosis in bile duct carcinoma].

Recent studies of erbB-2 expression have shown that the erbB-2 oncoprotein correlated with poor prognosis of patients with breast cancer. Surgical treatment of the bile duct carcinoma is currently unsatisfactory. To evaluate erbB-2 oncoprotein as a marker of prognosis, we analyzed 68 bile duct carcinomas immunohistologically, using monoclonal antibody against erbB-2 oncoprotein, as well as clinicopathological data and outcome. High incidence of expression of erbB-2 oncoprotein was shown in bile duct carcinoma. Positive rates of erbB-2 oncoprotein correlated with stage of bile duct carcinoma. Survival of patients with erbB-2 expression cancer was shorter than those without erbB-2 expression cancer and erbB-2 expression has a prognostic value in bile duct carcinoma.

A retrospective analysis of 335 Japanese lung cancer patients who responded to initial gefitinib treatment.

BACKGROUND: Gefitinib treatment results in considerably better progression-free survival compared with that of platinum doublets in the first line treatment of nonsmall-cell lung cancer (NSCLC) carrying an activating epidermal growth factor receptor (EGFR) mutation. Some patients who respond to gefitinib have an overall survival (OS) of more than 5 years, whereas other initial responders do less well. Although there has been considerable effort made to elucidate the mechanisms of acquired resistance, there have only been a few studies that addressed the effect of clinical backgrounds and treatment histories on the survival of the patients who had responded to an EGFR-tyrosine kinase inhibitor (TKI). In this study, we especially focused on the clinical benefit of EGFR-TKI administration after progression. PATIENTS AND METHODS: We retrospectively analyzed consecutive patients with advanced NSCLC who were diagnosed before October 2010, treated with gefitinib after July 2002, and responded to it. The primary objective of this study was to evaluate how clinical backgrounds and treatment histories influence survival of the patients who respond to gefitinib. The secondary objectives were to evaluate the safety of long-term gefitinib use and to establish the optimal treatment sequence using a dynamic treatment regimen analysis (DTRA). RESULTS: A total of 335 patients were recruited. Twenty-eight (8.4%) patients survived more than 5 years. Sixty-five and 93 patients received gefitinib as rechallenge and beyond progressive disease (BPD), respectively. A statistically significant difference in OS was observed between the patients who underwent gefitinib rechallenge and those who did not rechallenge (median: 1272 days vs. 774 days; p < 0.001), a result supported by a DTRA. Patients treated with gefitinib BPD also showed a tendency of longer survival. CONCLUSIONS: Gefitinib rechallenge and BPD played a central role in long term survival of the patients who initially responded to gefitinib.