SEARCH

SEARCH BY CITATION

Keywords:

  • pulmonary metastases;
  • miliary metastases;
  • epidermal growth factor receptor gene mutation;
  • tyrosine kinase inhibitor;
  • lung cancer

Abstract

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONFLICT OF INTEREST DISCLOSURES
  7. REFERENCES

BACKGROUND:

Although the association of multiple pulmonary metastases, and particularly miliary metastases, with response to gefitinib treatment in patients with nonsmall cell lung cancer has been reported, the association of miliary pulmonary metastases with epidermal growth factor receptor gene (EGFR) mutations remains unclear.

METHODS:

The authors retrospectively investigated the association of diffuse, random pulmonary metastases in patients with lung adenocarcinoma. The study included 163 Japanese patients who had unresectable, advanced lung adenocarcinoma diagnosed between April 2003 and March 2010. Computed tomography scans that were obtained at the time of diagnosis were analyzed by 2 investigators. For the purposes of this study, diffuse, random pulmonary metastases were defined as multiple nodules (n = 50; ≤3 cm in greatest dimension) distributed diffusely and randomly throughout the lungs.

RESULTS:

Of 163 patients, 55 had pulmonary metastases, and EGFR mutations were detected in 22 of those 55 patients. The mutations were identified preferentially among women (P = .15) and were identified significantly among patients who had a smoking history of <10 pack-years (P = .0057). Diffuse, random pulmonary metastases were identified in 11 of 22 patients who had EGFR mutations and in 4 of 33 patients who had the wild-type EGFR (P = .0043). On the basis of multivariate analyses, EGFR mutations were associated independently with a smoking history of <10 pack-years (P = .026) and with diffuse, random pulmonary metastases (P = .012).

CONCLUSIONS:

When patients with lung adenocarcinomas who had EGFR mutations developed pulmonary metastases, they tended to be diffuse and random, including military metastases. However, such metastases were much less common in patients who had lung adenocarcinomas with wild-type EGFR. Cancer 2011. © 2010 American Cancer Society.

The epidermal growth factor receptor (EGFR) is recognized as an important molecular target in cancer therapy.1 Because patients with nonsmall cell lung cancer (NSCLC) who have somatic activating mutations of the EGFR gene generally respond to EGFR tyrosine kinase inhibitors (TKIs) (gefitinib or erlotinib), such EGFR mutations are very important markers and are useful in deciding the course of treatment for patients with NSCLC.2-4

Although miliary pulmonary metastases are observed most often in patients with thyroid carcinoma,5 these metastases sometimes are observed in patients with lung cancer; an association between multiple pulmonary metastases, particularly miliary metastases, and response to gefitinib therapy in patients with NSCLC has been reported.6 Moreover, we recently reported that 1 patient with thyroid carcinoma who had an EGFR mutation7 had miliary pulmonary metastases and responded to gefitinib therapy. From this finding, we hypothesized that, for cancers in which the patient has accompanying EGFR mutation(s), including NSCLC and thyroid carcinoma, miliary pulmonary metastases often develop. In this article, we retrospectively investigated the association of diffuse, random pulmonary metastases, including miliary metastases, with EGFR mutations in patients with lung adenocarcinoma.

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONFLICT OF INTEREST DISCLOSURES
  7. REFERENCES

Patients

Japanese patients (n = 163) with unresectable, advanced lung adenocarcinoma who were diagnosed between April 2003 and March 2010 and who had their tumors analyzed for EGFR gene mutation at Kyoto University Hospital were enrolled in this study. Patient characteristics are listed in Table 1. We obtained written informed consent from all patients.

Table 1. Patient Characteristics (n=55)
CharacteristicNo. of Patients (%)
  • EGFR indicates epidermal growth factor receptor; TKIs, tyrosine kinase inhibitors.

  • a

    Performance status was evaluated before the administration of EGFR-TKIs.

Median/mean age [range], y68/67.7 [35-86]
Sex 
 Women31 (56.4)
 Men24 (43.6)
Smoking status 
 Nonsmoker25 (45.5)
 Smoker30 (54.5)
  Former23 (41.8)
  Current7 (12.7)
Performance statusa 
 0-147 (85.5)
 2-48 (14.5)
Administration of EGFR-TKIs 
 Yes31 (56.4)
 No24 (43.6)
First or second-line therapy with EGFR-TKIs 
  Yes24 (43.6)
  No31 (56.4)
EGFR 
 Mutated22 (40)
 Wild type33 (60)
Table 2. Clinical Characteristics of Patients With Pulmonary Metastases (n=55)
CharacteristicNo. of PatientsP
Mutated EGFRWild-Type EGFR
  • EGFR indicates epidermal growth factor receptor; TKIs, tyrosine kinase inhibitors; BAC, bronchioloalveolar pattern.

  • a

    Statistically significant in Chi square test or Fisher exact test (P < .05).

No./total no. of patients22/7733/86.19
Age, y   
 <701319.91
 ≥70914 
Sex   
 Men717 
 Women1516.15
Smoking status, pack-years   
  <101713 
  ≥10520.0057a
Performance status   
 0-11928 
 2-435.88
Pulmonary metastasis pattern   
  Diffuse random (miliary)11 (7)4 (1) 
  Others (BAC)11 (3)29 (7).0043a/.0049a

EGFR Mutational Analysis

Formalin-fixed, paraffin-embedded tissue blocks or cytologic samples were used for DNA analysis. We adopted the peptic nucleic acid-locked nucleic acid (PNA-LNA) polymerase chain reaction (PCR) clamp method, according to previously described protocols.8 Briefly, PNA clamp primers inhibit amplification of the wild-type sequence, and LNA probes are used to detect specific mutant sequences in the presence of wild-type sequences. A synergistic effect of these primers causes specific PCR amplification of mutant sequences. Specific PNA-LNA probe sets for each mutation were developed to detect >95% of the EGFR mutations reported previously in Japan.9

Imaging Studies

Two physicians who were blinded to results from the EGFR mutational analyses reviewed the chest computed tomography (CT) scans, including high-resolution CT scans, that were obtained at the time of lung cancer diagnosis. For the purposes of this study, diffuse, random pulmonary metastases, including miliary metastases, were defined as multiple nodules (a count ≥50 nodules and ≤3 cm in greatest dimension) that were distributed diffusely and randomly throughout the lungs. We used a previous definition of miliary pulmonary metastases,10 that is, profuse, tiny, discrete, rounded pulmonary opacities (≤3 mm in greatest dimension) generally uniform in size that are distributed diffusely and randomly throughout the lungs (Figs. 1-3). To avoid confusion, we distinguished a bronchioloalveolar carcinoma (BAC) pattern, which appears as centrolobular distribution (Fig. 4).

thumbnail image

Figure 1. These chest computed tomography images from a human aged 35 years who was a current smoker with an epithelial growth factor receptor gene mutation (L858R) reveal miliary pulmonary metastases. (A) Profuse, tiny, discrete, rounded, pulmonary opacities that generally are uniform in size are distributed diffusely throughout the lungs. A primary lesion was identified in the right upper lobe (arrow). (B) Four weeks after the initiation of gefitinib, the patient achieved a partial response.

Download figure to PowerPoint

thumbnail image

Figure 2. These chest computed tomography images from a women aged 67 years who was a nonsmoker with an epithelial growth factor receptor gene mutation (L858R) reveal diffuse, random pulmonary (nonmiliary) metastases. (A) Multiple nodules are distributed diffusely throughout the lungs and a primary lesion in the right upper lobe (arrow). The nodules are not uniform in size. (B) Four weeks after the initiation of erlotinib, the patient achieved a partial response.

Download figure to PowerPoint

thumbnail image

Figure 3. These chest computed tomography images from a women aged 79 years who was an exsmoker with the wild-type epithelial growth factor receptor gene reveal miliary pulmonary metastases. (A) Bilateral pleural effusions and profuse, tiny, discrete, rounded pulmonary opacities that generally are uniform in size are distributed diffusely throughout the lungs. (B) Four weeks after the initiation of gefitinib, the patient achieved a partial response.

Download figure to PowerPoint

thumbnail image

Figure 4. These chest computed tomography images from a women aged 36 years who was an exsmoker with the wild-type epithelial growth factor receptor gene reveal a bronchioloalveolar carcinoma pattern. (A) Patchy consolidation, ground-glass opacity, and centrolobular nodules are distributed bilaterally in the lower lungs. (B) Four weeks after the initiation of gefitinib, she developed progressive disease.

Download figure to PowerPoint

Statistical Analysis

The univariate correlation between each independent variable was examined using either the chi-square test or the Fisher exact test. A multivariate logistic regression model was applied to estimate odds ratios (ORs) and 95% confidence intervals (CIs). Only those variables with P values <.1 in univariate analysis were included in the multivariate analysis. All tests were 2-tailed, and P values <.05 were considered statistically significant. All preceding statistical analyses were performed using JMP 8 software (SAS Institute, Cary, NC).

RESULTS

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONFLICT OF INTEREST DISCLOSURES
  7. REFERENCES

EGFR mutations were detected in 77 of 163 patients (47%) and were not detected in 86 of 163 patients (53%). Twenty-two of 77 patients who had EGFR mutations had lung metastases (29%), and 33 of 86 patients with wild-type EGFR had pulmonary metastases (38%; P = .19; chi-square test). The clinical characteristics of the 55 patients who had pulmonary metastases are summarized in Table 1. The profiles of patients with EGFR mutations were similar to those reported previously.11, 12 The EGFR mutations were identified preferentially (but not significantly) among women (15 of 31 patients; P = .15; chi-square test) but were identified significantly in patients who had a smoking history of <10 pack-years (17 of 30 patients; P = .0057; chi-square test). Diffuse, random pulmonary metastases and miliary metastases were identified in 11 patients (50%) and 7 patients (32%), respectively, of the 22 patients who had EGFR mutations and in 4 patients (12%) and 1 patient (3%), respectively, of the 33 patients who had wild-type EGFR. EGFR mutations were associated significantly with both diffuse, random pulmonary metastases and miliary metastases (P = .0043 and P = .0049, respectively; Fisher exact test) (Table 2). In contrast, EGFR mutations were not associated with a BAC pattern (P = .72; Fisher exact test).

EGFR-TKIs were administered to 31 of 55 patients who had pulmonary metastases, and 19 of those 31 patients (61%) achieved a partial response (Table 3). EGFR-TKIs were more administered frequently to patients who had EGFR mutations (18 of 22 patients; 82%) than to patients who had the wild-type EGFR gene (13 of 33 patients; 39%; P = .0024; Fisher exact test). The response rate to EGFR-TKIs was higher preferentially (but not significantly) among women (15 of 22 patients; P = .25; Fisher exact test) and among patients who had a smoking history of <10 pack-years (15 of 21 patients; P = .13; Fisher exact test). In contrast, the response rate was significantly higher among patients who had EGFR mutations (16 of 18 patients; 89%) than among patients who had the wild-type EGFR gene (3 of 13 patients; 23%; P = .0005; Fisher exact test). In addition, the response rate was significantly higher in patients who had diffuse, random pulmonary metastases (11 of 13 patients; 85%) than in patients who had other pulmonary metastases (8 of 18 patients; 44%; P = .032; Fisher exact test). Four of the 15 patients who had diffuse, random pulmonary metastases had the wild-type EGFR gene. It is noteworthy that 2 of those 4 patients achieved a partial response to gefitinib (Fig. 3).

Table 3. Clinical Characteristics of Patients With Pulmonary Metastases Who Received Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor Treatment (n=31)
CharacteristicEGFR-TKI ResponseP
PRSD or PD
  • EGFR indicates epidermal growth factor receptor; TKI, tyrosine kinase inhibitor; PR, partial response; SD, stable disease; PD, progressive disease; BAC, bronchioloalveolar pattern.

  • a

    Statistically significant in Chi square test or Fisher exact test (P < .05).

No. of Patients1912
Age, y   
 <7099 
 ≥70103.16
Sex   
 Men45 
 Women157.25
Smoking status, pack-years   
 <1046 
 ≥10156.13
Performance status   
 0-11711 
 2-421.84
No. of previous chemotherapy regimens   
  0-1186 
  ≥216.007a
Pulmonary metastasis pattern   
 Diffuse random (miliary)11 (6)2 (0) 
 Others (BAC)8 (1)10 (3).032/.059a
EGFR   
 Mutated1610 
 Wild type32.0005a

We constructed a multivariate logistic regression model to identify the factors associated significantly with EGFR mutations and the response rate in this cohort. EGFR mutations were associated independently with a smoking history of <10 pack-years (OR, 4.40; 95%CI, 1.25-17.61; P = .026) and with diffuse, random pulmonary metastases (OR, 6.12; 95%CI, 1.58-27.97; P = .012) (Table 4). In contrast, the response rate was associated independently only with EGFR mutations (OR, 44.38; 95%CI, 4.28-1602.28; P = .0075) (Table 5). “Miliary metastases” were not analyzed, because the number of patients with such metastases was too small, and these were included in the “diffuse, random pulmonary metastases” category.

Table 4. Association Between Patient Characteristics and Epidermal Growth Factor Receptor Mutations
VariableOR (95% CI)P
  • OR indicates odds ratio; CI, confidence interval; BAC, bronchioloalveolar pattern.

  • a

    Statistically significant in logistic regression model analysis (P < .05).

Univariate analysis  
 Age (<70 y/≥70 y)1.06 (0.36-3.24).91
 Sex (women/men)2.28 (0.75-7.34).15
 Smoking history (<10 pack-years/≥10 pack-years)5.23 (1.63-19.23).0077a
 Performance status (0 or 1/2)1.13 (0.25-6.04).88
 Diffuse random pulmonary metastases (yes/no)7.25 (2.03-30.90).0037a
 BAC pattern pulmonary metastases (no/yes)1.69 (0.41-9.09).48
Multivariate analysis  
 Smoking history (<10 pack-years/≥10 pack-years)4.40 (1.25-17.61).026a
 Diffuse random pulmonary metastases (yes/no)6.12 (1.58-27.97).012a
Table 5. Association Between Patient Characteristics and Response to Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor Treatment
VariableOR (95% CI)P
  1. OR indicates odds ratio; CI, confidence interval; BAC, bronchioloalveolar pattern; EGFR, epidermal growth factor receptor. aStatistically significant in logistic regression model analysis (P < .05).

Univariate analysis  
 Age (≥70 y/<70 y)3.33 (0.73-18.87).14
 Sex (women/men)2.68 (0.55-14.08).23
 Smoking history (<10 pack-years/≥10 pack-years)3.75 (0.78-19.82).10
 Performance status (≥2/0 or 1)1.30 (0.11-29.41).84
 No. of previous chemotherapy regimens (0 or 1/≥2)18.00 (2.43-378.61)014a
 Diffuse random pulmonary metastases (yes/no)6.88 (1.35-53.43).033a
 BAC pattern pulmonary metastases (no/yes)5.88 (0.66-131.57).14
 EGFR (mutated/wild type)26.67 (4.51-250.91).0010a
Multivariate analysis  
 No. of previous chemotherapy regimens (0 or 1/≥2)13.06 (0.94-516.25).087
 Diffuse random pulmonary metastases (yes/no)9.61 (0.75-305.60).12
 EGFR (mutated/wild type)44.38 (4.28-1602.28).0075a

DISCUSSION

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONFLICT OF INTEREST DISCLOSURES
  7. REFERENCES

Although this was a small, retrospective study, 11 of the 15 patients who had diffuse, random pulmonary metastases had EGFR mutations (73%), and EGFR mutations were associated independently with diffuse, random pulmonary metastases. That is, patients who had lung adenocarcinoma with EGFR mutations tended to develop diffuse, random pulmonary metastases, including miliary metastases. However, diffuse, random pulmonary metastases were much less common in lung adenocarcinomas with wild-type EGFR.

The reason for this association is unclear. A random pulmonary metastatic pattern means that hematogenous metastasis is associated with angiogenesis.13, 14 It is long established that EGFR and its ligands play important roles in tumorigenesis.15 However, EGFR signaling also may play an important role in cancer progression. Because EGFR signaling regulates the synthesis and secretion of several different angiogenic growth factors in tumor cells (ie, vascular endothelial growth factor, interleukin-8, and basic fibroblast growth factor), EGFR mutations that accompany cancer, including NSCLC and thyroid carcinoma, tend to develop angiogenic metastases, such as diffuse, random pulmonary metastases.16

On the basis of our multivariate analysis, the response rate to EGFR-TKIs was associated independently with EGFR mutations but not with diffuse, random pulmonary metastases. This finding may have been because most patients with diffuse, random pulmonary metastases also had EGFR mutations and had achieved a partial response to the EGFR-TKIs. That is, “diffuse, random pulmonary metastases” were associated strongly with EGFR mutations. It is noteworthy that 2 of the 4 patients who had diffuse, random pulmonary metastases and the wild-type EGFR achieved a partial response to gefitinib therapy. The PNA-LNA PCR clamp method that we adopted can detect >95% of the EGFR mutations reported previously in Japan,9 and its sensitivity is 97%.17 However, this method does not allow the detection of all EGFR mutations. We speculate that the 2 patients with the “wild-type EGFR” who achieved a partial response to gefitinib in fact had an “EGFR mutation.” EGFR-TKIs should be used in patients with diffuse, random pulmonary metastases even when the “wild-type EGFR” is present, because there is a possibility that such patients in fact have an “EGFR mutation.”

Although, according to some previous reports, BAC pathologic subtype was a predictor of response to gefitinib, and EGFR mutations were observed preferentially in tumors that had BAC features,18-20 others reported that there was no association between BAC subtype and EGFR mutations.21, 22 In our study population, there was no association between a BAC pattern and EGFR mutations or response to gefitinib. However, a “BAC pattern” based on imaging appearance may include pathologic BAC histology.

Although this was a small, retrospective study, we observed an association between EGFR mutations and diffuse, random pulmonary metastases, including miliary metastases. The method that we used to detect EGFR mutations cannot detect all “EGFR mutations.” Therefore, to avoid missing EGFR mutations, larger studies to identify the features of EGFR mutations associated with cancer should be performed. We speculate that NSCLC-associated EGFR mutations have behavior similar to that of thyroid carcinoma-associated EGFR mutations, such as the development of diffuse, random pulmonary metastases, including miliary metastases. In the future, it may be possible to establish a new category for “EGFR mutation-associated cancers” that would include NSCLC and thyroid carcinoma.

REFERENCES

  1. Top of page
  2. Abstract
  3. MATERIALS AND METHODS
  4. RESULTS
  5. DISCUSSION
  6. CONFLICT OF INTEREST DISCLOSURES
  7. REFERENCES