[Breast metastases from lung cancers with the EGFR mutation].
BACKGROUND
The breast is a rare site for metastases from lung cancers. Their occurrence in patients with adenocarcinoma which has the EGFR mutation is exceptional. In this context, it is sometimes difficult to differentiate a second primary breast cancer from a breast metastasis.


METHODS
We report the cases of two patients who developed breast metastases from lung adenocarcinoma that was TTF1 positive with a deletion of exon 19 of the EGFR gene. A non-smoking woman of Asian origin, presented with a solitary breast metastasis 29 months after being established on first-line chemotherapy. The second case was a Caucasian patient who was an active smoker presented with tumor progression with multiple metastases including involvement of both breasts 10 months after the start of treatment with a tyrosine kinase inhibitor. In both, tumor cells from the breast showed positive immunostaining for TTF1 and genotyping detected the presence of the deletion of exon 19 of the EGFR gene.


CONCLUSIONS
In patients with lung adenocarcinoma and EGFR mutation, immunohistochemical examination, including TTF1 and genotyping of synchronous breast tumour, is needed to confirm its metastatic nature and to guide treatment.
Service de pneumologie et d'oncologie thoracique, groupe hospitalier Nord Essonne, 159, rue du Président-François-Mitterrand, 91160 Longjumeau cedex 01, France. Electronic address: p.assouline@gh-nord-essonne.fr.
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Assouline
Service d'anatomie et de cytologie pathologiques, groupe hospitalier Nord Essonne, 91160 Longjumeau cedex 01, France.
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MB
Léger-Ravet
Service de biochimie et d'oncogénétique, hôpital Paul-Brousse, Assistance publique-Hôpitaux de Paris, 12, avenue Paul-Vaillant-Couturier, 94800 Villejuif, France.
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Saffroy
Service de biochimie et d'oncogénétique, hôpital Paul-Brousse, Assistance publique-Hôpitaux de Paris, 12, avenue Paul-Vaillant-Couturier, 94800 Villejuif, France.
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Hamelin
Service d'imagerie médicale, groupe hospitalier Nord Essonne, 91160 Longjumeau cedex 01, France.
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A
Bénissad
Service de pneumologie et d'oncologie thoracique, groupe hospitalier Nord Essonne, 159, rue du Président-François-Mitterrand, 91160 Longjumeau cedex 01, France.
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Husleag
Service de biochimie et d'oncogénétique, hôpital Paul-Brousse, Assistance publique-Hôpitaux de Paris, 12, avenue Paul-Vaillant-Couturier, 94800 Villejuif, France.
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A
Lemoine
Service de pneumologie et d'oncologie thoracique, groupe hospitalier Nord Essonne, 159, rue du Président-François-Mitterrand, 91160 Longjumeau cedex 01, France.
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Oliviéro
D000230:Adenocarcinoma / Q000235:genetics* / Q000473:pathology*; D000077192:Adenocarcinoma of Lung; D000368:Aged; D001943:Breast Neoplasms / Q000235:genetics / Q000556:secondary*; D066246:ErbB Receptors / Q000235:genetics*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000473:pathology*; D008875:Middle Aged; D009154:Mutation
C512478:EGFR protein, human; D066246:ErbB Receptors
Atypical metastatic site; Breast metastasis; Cancer bronchique; EGFR mutation; Lung cancer; Mutation EGFR; Mutation T790M; Métastase mammaire; Site métastatique atypique; T790M mutation