A very large number of clinical trials have been conducted in "pure" SCLC over the past several decades. As a result, evidence-based sets of guidelines for treating monophasic SCLC are available. While the current set of SCLC treatment guidelines recommend that c-SCLC be treated in the same manner as "pure" SCLC, they also note that the evidence supporting their recommendation is quite weak. It is likely, then, that the optimum treatment for patients with c-SCLC remains unknown. The current generally accepted standard of care for all forms of SCLC is concurrent chemotherapy (CT) and thoracic radiation therapy (TRT) in LD, and CT only in ED. For complete responders (patients in whom all evidence of disease disappears), prophylactic cranial irradiation (PCI) is also given. TRT serves to increase the probability of total eradication of residual locoregional disease, while PCI aims to eliminate any micrometastases to the brain. Surgery is not often considered as a treatment option in SCLC (including c-SCLC) due to the high probability of distant metastases at the time of diagnosis. This paradigm was driven by early studies showing that the administration of systemic therapies resulted in improved survival as compared to patients undergoing surgical resection. Recent studies, however, have suggested that surgery for highly selected, very early-stage c-SCLC patients may indeed improve outcomes. Other experts recommend resection for residual masses of NSCLC components after complete local tumor response to chemotherapy and/or radiotherapy in c-SCLC. Although other combinations of drugs have occasionally been shown to be noninferior at various endpoints and in some subgroups of patients, the combination of cisplatin or carboplatin plus etoposide or irinotecan are considered comparable first-line regimens for SCLC. For patients who do not respond to first line therapy, or who relapse after complete remission, topotecan is the only agent which has been definitively shown to offer increased survival over best supportive care (BSC), although in Japan amirubicin is considered effective as salvage therapy. Importantly, c-SCLC is usually much more resistant to CT and RT than "pure" SCLC. While the mechanisms for this increased resistance of c-SCLC to conventional cytotoxic treatments highly active in "pure" SCLC remain mostly unknown, recent studies suggest that the earlier in its biological history that a c-SCLC is treated, the more likely it is to resemble "pure" SCLC in its response to CT and RT. Targeted agents In recent years, several new types of "molecularly targeted" agents have been developed and used to treat lung cancer. While a very large number of agents targeting various molecular pathways are being developed and tested, the main classes and agents that are now being used in lung cancer treatment include: * Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs): * Erlotinib (Tarceva) * Gefitinib (Iressa) * Cetuximab (Erbitux) * Inhibitors of vascular endothelial growth factor (VEGF) * Bevacizumab (Avastin) * Inhibitors of folate metabolism * Pemetrexed (Alimta) To date, most clinical trials of targeted agents, alone and in combination with previously tested treatment regimens, have either been ineffective in SCLC or no more effective than standard platinum-based doublets. While there have been no randomized clinical trials of targeted agents in c-SCLC, some<unk>  case series suggest that some may be useful in c-SCLC. Many targeted agents appear more active in certain NSCLC variants. Given that c-SCLC contains components of NSCLC, and that the chemoradioresistance of NSCLC components impact the effectiveness of c-SCLC treatment, these agents may permit the design of more rational treatment regimens for c-SCLC. EGFR-TKI's have been found to be active against variants exhibiting certain mutations in the EGFR gene. While EGFR mutations are very rare (<5%) in "pure" SCLC, they are considerably more common (about 15–20%) in c-SCLC, particularly in non-smoking females whose c-SCLC tumors contain an adenocarcinoma component. These patients are much more likely to have classical EGFR mutations in the<unk>  cell component of their tumors as well, and their tumors seem to be more likely to respond to treatment with EGFR-TKI's. EGFR-targeted agents appear particularly effective in papillary adenocarcinoma, non-mucinous bronchioloalveolar carcinoma, and adenocarcinoma with mixed subtypes. The role of VEGF inhibition and bevacizumab in treating SCLC remains unknown. Some studies suggest it may, when<unk>  with other agents, improve some measures of survival in SCLC patients and in some non-squamous cell variants of NSCLC. Pemetrexed has been shown to improve survival in non-squamous cell NSCLC, and is the first drug to reveal differential survival benefit in large cell lung carcinoma. C-SCLC appear to express female hormone (i.e. estrogen and/or progesterone) receptors in a high (50–67%) proportion of cases, similar to breast carcinomas. However, it is at present unknown whether blockade of these receptors affects the growth of c-SCLC.
Combined small-cell lung carcinoma
Salivary gland–like carcinoma of the lung
Epithelial-myoepithelial carcinoma of the lung
Adenosquamous lung carcinoma
Large-cell lung carcinoma
Basaloid squamous cell lung carcinoma
Mucinous cystadenocarcinoma of the lung
Sarcomatoid carcinoma of the lung