Synchronous lung cancer presenting with small cell carcinoma and adenocarcinoma

Targeted sequencing may facilitate differential diagnostics of pulmonary tumours: a case series

Background

Histopathological diagnosis is important for prognostication and choice of treatment in patients with cancer in the lung. Metastases to the lungs are common and need to be distinguished from primary lung cancer. Furthermore, cases with synchronous or metachronous primary lung cancers (although infrequent) are often handled differently than cases with lung cancer with intrapulmonary metastasis or relapse, respectively. In some cases, morphology and immunohistochemical staining is not sufficient for certain diagnosis.

Methods

The present study included six cases where molecular genetic analysis in form of pyrosequencing or targeted next-generation sequencing was of value for certain diagnosis of selected tumours in the lung.

Results

Two of the included cases were rare metastases to the lung; colorectal cancer with IHC profile consistent with primary lung cancer and malignant adenomyoepithelioma of the breast, respectively, where molecular genetic analysis was of aid for proving the relationship to the primary tumour. The other four cases were multiple lung adenocarcinomas where molecular genetic analysis was of aid to distinguish between intrapulmonary metastasis and synchronous tumour.

Conclusions

Comparison of molecular genetic profile may be an important tool for determination of relationship between tumours in some situations and should always be considered in unclear cases. Further studies on concordance and discordance of molecular genetic profiles between spatially or temporally different tumours with common origin may be helpful for improved diagnostics of pulmonary tumours.

Synchronous primary lung cancer presenting with small cell carcinoma and adenocarcinoma

Multiple synchronous primary lung cancers presenting with different histologic types are uncommon. Among reported cases with different histologic findings, only a few had small cell lung cancer (SCLC) and adenocarcinoma. This unusual combination of lung cancers has not been well reported. In this report, we describe two cases of synchronous primary lung cancer presenting with lymph node metastasis of SCLC and early-stage adenocarcinoma. Epidermal growth factor receptor (EGFR) mutation was not detected in either SCLC or adenocarcinoma in the two cases.

[Bifocal lung cancer: the same histology?]

Whereas synchronous lung cancer is rare, synchronous small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC) are exceptional. The authors report the case of a 61-year-old man with synchronous unilateral adenocarcinoma and small cell lung cancer, raising the question as to the need for the histology of all of the lesions in the same lobe or same lung as well as the treatment. The medical history, biology, CT and (18)F-FDG TEP-CT did not support a diagnosis of synchronous lung cancer. The prognosis was poor and only surgery could improve the prognosis. This is a rare case and illustrates the difficulty in the diagnosis of multiple lung cancer and the difficulty in treating synchronous lung cancer with different histologies (SCLC and NSCLC).

Clonality and prognostic implications of p53 and epidermal growth factor receptor somatic aberrations in multiple primary lung cancers

PURPOSE

For treatment decision and prognostic applications, we evaluated p53/epidermal growth factor receptor (EGFR) somatic aberrations in multiple primary lung cancers to differentiate multifocal tumors from intrapulmonary metastasis.

EXPERIMENTAL DESIGN

Fifty-eight multiple primary lung cancers of 1,037 patients in a 10-year period were identified to investigate somatic mutations and altered expression of p53 and EGFR for clonality assessment. Genomic DNA was extracted from microdissected cells of paraffin-embedded multiple primary lung cancer tissues. Overexpression and somatic mutations in exons of p53 (exons 5-8) and tyrosine kinase domain of EGFR (exons 18-22) were examined by immunohistochemical staining and DNA sequencing, respectively.

RESULTS

High frequency of somatic mutations in p53 (33 of 58, 56.9%) and/or EGFR (44 of 58, 75.9%) resulted in high discrimination rate of tumor clonality (50 of 58, 86.2%) of multiple primary lung cancers. Twenty-two cases (37.9%) were assessed as having the same clonality and 28 cases (48.3%) were determined as having different clonality, which further supported the carcinogenic theory of field cancerization. Notably, the occurrence of lymph node metastasis was more commonly observed in tumors with the same clonality (P = 0.045) and was associated with poor patient 5-year survival rate (P = 0.001). However, no correlation was found between tumor clonality and patient survival (P = 0.630). The EGFR somatic aberrations in 58 multiple primary lung cancers, including vascular invasion associated with EGFR overexpression (P = 0.012) and mutation (P = 0.025), further suggested the potential benefits of target therapy of inoperable multiple primary lung cancers.

CONCLUSIONS

Our results suggest that analysis of somatic alterations in p53 and EGFR can significantly improve the clonality assessment and impact management of multiple primary lung cancer patients.

Mutations of the P53 tumor suppressor gene as clonal marker for multiple primary lung cancers

OBJECTIVES

Second primary lung cancers are prevalent after treatment for initial lung cancer, and the lung is also one of the most frequent sites for recurrence after removal of early-stage lung cancer. The objective of the present study is to clarify the clonal origin of the second tumor with the p53 gene mutation used as a clonal marker.

METHODS

Of 794 consecutive patients who underwent pulmonary resection for primary lung cancer from 1980 to 1993, 22 required second pulmonary resection during the follow-up period, with a median interval of 38 months. We examined 16 of these patients for mutations of the p53 gene occurring in exons 5 through 8 by the polymerase chain reaction/single strand conformation polymorphism method. Differential diagnosis was also made on a morphologic basis, considering the degree of cellular differentiation and cytologic subtypes.

RESULTS

Nine of the 16 patients analyzed had at least one p53 mutation in their tumors. We were thus able to make molecular diagnoses for these patients. The mutational status of the p53 gene was discordant in all nine patients, suggesting a different clonal origin despite the fact that six of them had almost identical histologic features.

CONCLUSIONS

Analysis of p53 gene mutations was thus useful in distinguishing second primary lung cancers from recurrent tumors. The observed heterogeneity of p53 status was also in line with the "field cancerization" concept.