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Simple Summary: The evaluation of therapeutic approaches over a decade at a tertiary cancer center in Germany was undertaken due to the frequent and critical discussions surrounding the selection of chemotherapy regimens and the incorporation of prophylactic cranial irradiation (PCI) in the management of limited disease small cell lung cancer (LD-SCLC). We found significant differences in progression-free survival (PFS) and overall survival (OS) between patients treated with carboplatin and etoposide (CP) and those treated with cisplatin and etoposide (EP), with EP showing better outcomes. Concomitant chemotherapy was also associated with improved PFS and OS. Notably, PCI was found to significantly improve OS and showed a trend towards improved PFS. Female patients had better OS, and the type of chemotherapy and PCI remained independent predictors of survival. This research provides valuable insights into treatment patterns, outcomes, and survival predictors for LD-SCLC, emphasizing the importance of personalized treatment approaches and the potential benefits of PCI. However, the study's retrospective nature and sample-size limitations should be considered, highlighting the need for further prospective studies in this field. In this study, we investigated the outcomes and factors influencing treatment efficacy in 93 patients with limited disease small cell lung cancer (LD-SCLC), with a median age of 64 years. We focused on the impact of chemotherapy regimens, prophylactic cranial irradiation (PCI), and patient-related variables. The median follow-up for OS was 17.3 months. We observed a statistically significant difference in PFS between LD-SCLC patients treated with cisplatin and etoposide (EP) and those treated with carboplatin and etoposide (CP) (PFS: EP 13.63 months vs. CP 6.54 months, p < 0.01). Patients treated with EP had better overall survival (OS) than CP-treated patients (OS: EP 26.9 months vs. CP 16.16 months, p < 0.01). Concomitant chemotherapy was associated with improved PFS (p = 0.003) and OS (p = 0.002). Patients receiving PCI showed superior OS (p = 0.05) and a trend towards improved PFS (p = 0.057). Female gender was associated with better OS (p = 0.025). Most patients had an ECOG performance status of 0 (71%). This real-world study underscores the importance of multidisciplinary LD-SCLC management, emphasizing the roles of chemotherapy, radiotherapy, and PCI. These findings inform personalized treatment strategies and emphasize the need for prospective trials to validate these results and optimize LD-SCLC treatment. [ABSTRACT FROM AUTHOR]

Simple Summary: Identification of the optimal treatment strategy is challenging in elderly with non-small cell lung cancer (NSCLC). Outcomes (1) in elderly vs. younger patients and (2) with low-dose cisplatin vs. cisplatin/vinorelbine were studied. Elderly included more males, had a lower Karnofsky index, more comorbidities, and lower stages. Low-dose cisplatin patients had higher age, more comorbidities, and lower stages. We observed reduced dermatitis and dysphagia and increased anemia and thrombocytopenia in elderly, without increased ≥grade 3 toxicities. Low-dose cisplatin was less toxic than cisplatin/vinorelbine. Survival was lower in elderly vs. younger and comparable between both chemotherapy protocols. In elderly, gender, Karnofsky index, stage, and multimodal treatment (including additional surgery/systemic therapy) were prognostic factors. In elderly, we found acceptable toxicities with radiotherapy but the need for the improvement of outcomes. Multimodal strategies showed a favorable prognosis and can reasonably be considered. Low-dose cisplatin should be discussed on an individual basis due to favorable toxicity and outcomes. Identification of the optimal treatment strategy is challenging in elderly with localized non-small cell lung cancer (NSCLC). Concurrent chemotherapy with low-dose cisplatin represents an option for elderly. Outcomes (1) in elderly (≥70 years, n = 158) vs. younger patients (n = 188) and (2), independently of age, in definitive radiochemotherapy, with low-dose cisplatin (n = 125) vs. cisplatin/vinorelbine (n = 76) were studied. Elderly included more males, had a lower Karnofsky index, more comorbidities, and lower stages. Low-dose cisplatin patients (vs. cisplatin/vinorelbine) had higher age, more comorbidities, and lower stages. We observed reduced dermatitis and dysphagia and increased anemia and thrombocytopenia in elderly vs. younger patients, without increased ≥grade 3 toxicities. Low-dose cisplatin was less toxic than cisplatin/vinorelbine. Survival outcomes were lower in elderly vs. younger and comparable between low-dose cisplatin and cisplatin/vinorelbine. In elderly, gender, Karnofsky index, stage, and multimodal treatment (including additional surgery/systemic therapy) were identified as prognostic factors. In conclusion, we found evidence for an acceptable toxicity profile and the need for improvement of outcomes in elderly with localized NSCLC. Multimodal strategies (including additional surgery/systemic treatment) showed favorable outcomes and should be reasonably considered in elderly who are deemed fit enough. Low-dose cisplatin should be discussed on an individual basis due to favorable toxicity and outcomes. [ABSTRACT FROM AUTHOR]

Simple Summary: We studied clinical aspects in central vs. peripheral tumors (n = 78 patients) and applied the internal organ at risk volume (IRV) concept (n = 35 patients) in stereotactic body radiation therapy (SBRT) for centrally located non-small cell lung cancer (NSCLC). We found lower biologically effective doses, larger planning target volume sizes, higher lung doses, and worse locoregional control for central tumors when compared with peripheral tumors. We here provide evidence that organ motion/volume changes could be more pronounced in males and tall patients, and less pronounced in cases of higher body mass index. Applying the IRV concept (retrospectively, without new optimization), the normal tissue complication probabilities increased >10% for the bronchial tree in three patients. This study emphasizes the need to optimize methods to balance dose escalation with toxicities in central tumors. Since recent studies have made efforts to further subclassify central tumors to refine treatment, the IRV concept should be considered for optimal risk assessment. The internal organ at risk volume (IRV) concept might improve toxicity profiles in stereotactic body radiation therapy (SBRT) for non-small cell lung cancer (NSCLC). We studied (1) clinical aspects in central vs. peripheral tumors, (2) the IRV concept in central tumors, (3) organ motion, and (4) associated normal tissue complication probabilities (NTCPs). We analyzed patients who received SBRT for NSCLC (clinical aspects, n = 78; motion management, n = 35). We found lower biologically effective doses, larger planning target volume sizes, higher lung doses, and worse locoregional control for central vs. peripheral tumors. Organ motion was greater in males and tall patients (bronchial tree), whereas volume changes were lower in patients with a high body mass index (BMI) (esophagus). Applying the IRV concept (retrospectively, without new optimization), we found an absolute increase of >10% in NTCPs for the bronchial tree in three patients. This study emphasizes the need to optimize methods to balance dose escalation with toxicities in central tumors. There is evidence that organ motion/volume changes could be more pronounced in males and tall patients, and less pronounced in patients with higher BMI. Since recent studies have made efforts to further subclassify central tumors to refine treatment, the IRV concept should be considered for optimal risk assessment. [ABSTRACT FROM AUTHOR]

The pandemic raised a discussion about the postponement of medical interventions for non-small cell lung cancer (NSCLC). We analyzed the characteristics of pretreatment diagnostic assessment in the pandemic and the influence of diagnostic assessment on outcomes. A total of 96 patients with stereotactic body radiation therapy (SBRT) for NSCLC were included. The number of patients increased from mean 0.9 (2012–2019) to 1.45 per month in the COVID era (p < 0.05). Pandemic-related factors (contact reduction, limited intensive care unit resources) might have influenced clinical decision making towards SBRT. The time from pretreatment assessment (multidisciplinary tumor board decision, bronchoscopy, planning CT) to SBRT was longer during the COVID period (p < 0.05). Reduced services, staff shortage, or appointment management to mitigate infection risks might explain this finding. Overall survival, progression-free survival, locoregional progression-free survival, and distant progression-free survival were superior in patients who received a PET/CT scan prior to SBRT (p < 0.05). This supports that SBRT guidelines advocate the acquisition of a PET/CT scan. A longer time from PET/CT scan/conventional staging to SBRT (<10 vs. ≥10 weeks) was associated with worse locoregional control (p < 0.05). The postponement of diagnostic or therapeutic measures in the pandemic should be discussed cautiously. Patient- and tumor-related features should be evaluated in detail. [ABSTRACT FROM AUTHOR]

Objectives/Hypothesis External auditory canal cancer is rare and carries a poor prognosis. To date, only a few studies provide evidence for clinical decision making in multimodal treatment. Methods Retrospective chart review of 36 cases in three tertiary referral centers. Results Thirteen patients were treated by surgery alone, 18 by surgery with adjuvant chemoradiotherapy (CRT) and five by primary CRT. Clear surgical margins (R0) were obtained in 19 patients and positive margins (R1) in 12. The 5-year overall survival and local control rates were 59.4% and 74.2% with R0 status versus 56.6% and 26.3% with R1 status. The 5-year overall survival and local control rates were 46.2% and 70.7% with surgery alone, 78.1% and 43.2% with surgery and adjuvant CRT, and 25.0% and 80.0% with primary CRT. Conclusion Surgery is integral to the management of external auditory canal cancer, whereas CRT is necessary as an adjuvant or primary treatment, depending on tumor stage. Level of Evidence 4. Laryngoscope, 125:2107-2112, 2015 [ABSTRACT FROM AUTHOR]

Simple Summary: Genetic variability in transforming growth factor beta pathway (TGFB) has been reported to affect adverse events in radiotherapy. We investigated 40 germline polymorphisms in peripheral blood cells, covering the entire common genetic variability in the TGFβ1 ligand (gene TGFB1) and the TGFβ receptor-1 (TGFBR1) in 240 patients treated with primary radiotherapy for prostate cancer. Human lymphoblastoid cell lines (LCLs) were used to assess whether TGFB1 and TGFBR1 polymorphisms impact DNA repair capacity following single irradiation with 3 Gy. Upon adjustment for multiplicity testing, for one polymorphism (rs10512263 in TGFBR1, C-variant allele, n = 35), a statistically significant association with acute radiation toxicity was observed. As a possible mechanistic explanation, reduced DNA repair capacity in carriers of the C-allele after irradiation in LCLs was discovered. This finding has a possible relevance for a plethora of (patho)physiological conditions. Genetic variability in transforming growth factor beta pathway (TGFB) was suggested to affect adverse events of radiotherapy. We investigated comprehensive variability in TGFB1 (gene coding for TGFβ1 ligand) and TGFBR1 (TGFβ receptor-1) in relation to radiotoxicity. Prostate cancer patients treated with primary radiotherapy (n = 240) were surveyed for acute and late toxicity. Germline polymorphisms (n = 40) selected to cover the common genetic variability in TGFB1 and TGFBR1 were analyzed in peripheral blood cells. Human lymphoblastoid cell lines (LCLs) were used to evaluate a possible impact of TGFB1 and TGFBR1 genetic polymorphisms to DNA repair capacity following single irradiation with 3 Gy. Upon adjustment for multiplicity testing, rs10512263 in TGFBR1 showed a statistically significant association with acute radiation toxicity. Carriers of the Cytosine (C)-variant allele (n = 35) featured a risk ratio of 2.17 (95%-CI 1.41–3.31) for acute toxicity ≥ °2 compared to Thymine/Thymine (TT)-wild type individuals (n = 205). Reduced DNA repair capacity in the presence of the C-allele of rs10512263 might be a mechanistic explanation as demonstrated in LCLs following irradiation. The risk for late radiotoxicity was increased by carrying at least two risk genotypes at three polymorphic sites, including Leu10Pro in TGFB1. Via comprehensive genotyping of TGFB1 and TGFBR1, promising biomarkers for radiotoxicity in prostate cancer were identified. [ABSTRACT FROM AUTHOR]

Simple Summary: Locally advanced head and neck squamous cell carcinomas (HNSCC) are often managed with surgery and postoperative radiochemotherapy (RCT). Until now, a deeper understanding of specific management strategies for elderly patients was lacking. In the present study, we compared patients ≥70 years of age and younger patients treated with postoperative RCT for HNSCC. All patients were treated with modern radiotherapy techniques (IMRT/VMAT). Elderly patients had more comorbidities. In addition, they less frequently received concomitant systemic treatment. The rates of mucositis and dermatitis were lower in patients ≥70 years. Elderly patients had significantly worse overall survival and progression-free survival. Locoregional and distant control were comparable in elderly and younger patients. In conclusion, postoperative radiochemotherapy is a safe and effective treatment option in patients ≥70 years. In light of comorbidities and poor survival rates, potential benefits and harms of radiotherapy and concomitant systemic treatment should be weighed carefully for this age group. Locally advanced head and neck squamous cell carcinomas (HNSCC) are often managed with surgery followed by postoperative radiochemotherapy (RCT). With the general increase in life expectancy, the proportion of elderly patients with HNSCC is expected to grow rapidly. Until now, a deeper understanding of specific management strategies for these patients in clinical routine was lacking. In the present study, we compared elderly patients (≥70 years, n = 52) and younger patients (n = 245) treated with postoperative RCT for HNSCC at our tertiary cancer center. All patients were irradiated with modern radiotherapy techniques (IMRT/VMAT). Patients ≥70 years of age had more comorbidities. Additionally, elderly patients less frequently received concomitant systemic treatment. The rates of mucositis and dermatitis were lower in patients ≥70 years. Elderly patients had significantly worse overall and progression-free survival. Locoregional and distant control were comparable in elderly and younger patients. In conclusion, postoperative RCT is a safe and effective treatment option in patients ≥70 years. In light of comorbidities and poor overall survival rates, benefits and harms of radiotherapy and concomitant systemic treatment should be weighed carefully. When exclusively applying up-to-date radiotherapy techniques with, at the same time, careful use of concomitant systemic therapy, favorable acute toxicity profiles are achieved. [ABSTRACT FROM AUTHOR]

Simple Summary: In Western countries, the lifetime risk for rectal cancer is around 1.5%. Most patients are diagnosed with locally advanced stages. For these patients, multimodal treatment comprising radiotherapy, chemotherapy, and surgery has become the standard of care. Whereas excellent local control is achieved, still about one out of three dies from this disease. Cytotoxicity of radiochemotherapy substantially involves reactive oxygen species (ROS). In ROS-related genes, we selected eight inherited variants, for which the literature reports functional or medical effects and which occur frequently in the general population. These variants were assessed whether they impact the clinical outcome of patients with rectal cancer. We found that the OGG1 Cys326 variant, which affected 37% of the 287 patients in the sample, was strongly linked with a worse outcome, in particular cancer-specific survival. Screening for this variant may identify a particular risk subgroup of patients who may be considered for more intensified therapy and aftercare. Despite excellent loco-regional control by multimodal treatment of locally advanced rectal cancer, a substantial portion of patients succumb to this disease. As many treatment effects are mediated via reactive oxygen species (ROS), we evaluated the effect of single nucleotide polymorphisms (SNPs) in ROS-related genes on clinical outcome. Based on the literature, eight SNPs in seven ROS-related genes were assayed. Eligible patients (n = 287) diagnosed with UICC stage II/III rectal cancer were treated multimodally starting with neoadjuvant radiochemotherapy (N-RCT) according to the clinical trial protocols of CAO/ARO/AIO-94, CAO/ARO/AIO-04, TransValid-A, and TransValid-B. The median follow-up was 64.4 months. The Ser326Cys polymorphism in the human OGG1 gene affected clinical outcome, in particular cancer-specific survival (CSS). This effect was comparable in extent to the ypN status, an already established strong prognosticator for patient outcome. Homozygous and heterozygous carriers of the Cys326 variant (n = 105) encountered a significantly worse CSS (p = 0.0004 according to the log-rank test, p = 0.01 upon multiple testing adjustment). Cox regression elicited a hazard ratio for CSS of 3.64 (95% confidence interval 1.70–7.78) for patients harboring the Cys326 allele. In a multivariable analysis, the effect of Cys326 on CSS was preserved. We propose the genetic polymorphism Ser326Cys as a promising biomarker for outcome in rectal cancer. [ABSTRACT FROM AUTHOR]

Simple Summary: Intensity-modulated radiotherapy (IMRT) is the standard of care in definitive chemoradiotherapy (CRT) for anal cancer. Only a limited number of studies have analyzed the clinical results with VMAT (volumetric modulated arc therapy, the advanced form of IMRT). We conducted a retrospective study on patients treated at our institution. We compared the outcomes of VMAT-treated and 3DCRT (3D conformal radiotherapy)-treated patients. VMAT reduced acute toxicities (i.e., primarily dermatitis and enteritis) to a great extent. Additionally, VMAT relevantly improved treatment compliance (i.e., less CRT interruptions/delays, shorter overall treatment time, and higher absolute 5-fluorouracil dose applied). Finally, we found improved cancer-specific survival and distant control in VMAT-treated patients. The present study underlines the great progress that has been achieved with IMRT/VMAT in the CRT of anal cancer. Our study is the first to demonstrate an improvement in treatment compliance and outcomes with VMAT. Future studies could address whether VMAT is advantageous when compared to conventional IMRT. Background: Intensity-modulated radiotherapy (IMRT) is the standard of care in chemoradiotherapy (CRT) for anal cancer. Until now, only a limited number of studies have analyzed the results with VMAT (volumetric modulated arc therapy). We conducted a retrospective study on patients treated at our institution. Patients and Methods: We included patients who received curative CRT for anal cancer. We compared VMAT-treated and 3DCRT (3D conformal radiotherapy)-treated patients. We analyzed toxicities (acute: CTCAE criteria; late: LENT/SOMA criteria), treatment compliance, overall survival, cancer-specific survival (CSS), distant control (DC), and locoregional control. Results: A total of 149 patients (3DCRT: n = 87, VMAT: n = 62) were included. The median follow-up was longer in 3DCRT-treated patients (3DCRT: 61.3 months; VMAT: 39.1 months; p < 0.05). VMAT-treated patients had more G3 tumors (3DCRT: 12/87 (13.8%); VMAT: 18/62 (29.0%), p < 0.001). VMAT reduced acute toxicities ≥grade 3 (3DCRT: n = 48/87 (55.2%); VMAT: n = 11/62 (17.7%), p < 0.001). VMAT improved treatment compliance (less interruptions/delays) (3DCRT: 37/87, 42.5%; VMAT: 4/62, 6.5%; p < 0.001), provided a shorter median overall treatment time (3DCRT: 41 days; VMAT: 38 days; p = 0.02), and gave a higher median absolute 5-fluorouracil dose (3DCRT: 13,700 mg; VMAT: 14,400 mg; p = 0.001). Finally, we found improved CSS (p = 0.02; 3DCRT: 81.9% at 3 years; VMAT: 94.1% at 3 years) and DC (p = 0.01; 3DCRT: 89.4% at 3 years; VMAT: 100.0% at 3 years) with VMAT. Summary: Our study is the first to demonstrate improved treatment compliance and outcomes with VMAT for anal cancer. Previous studies have indicated that organs at risk sparing might be more improved with the use of VMAT vs. with conventional IMRT. Future studies should address whether these advantages lead to a further reduction in CRT-associated morbidity. [ABSTRACT FROM AUTHOR]

Simple Summary: We retrospectively studied outcomes in patients treated with preoperative radiochemotherapy and surgery for esophageal squamous cell cancer. We put a special focus on the comparison of patients treated with 5-fluorouracil/cisplatin ('Walsh') or carboplatin/paclitaxel ('CROSS'). First, the higher age and more comorbidities of 'CROSS' patients, along with a shorter intensive care/intermediate care unit stay, might reflect an improvement in supportive and surgical/perioperative procedures in the periods. Second, the 'CROSS' patients experienced more hematologic toxicity and were less likely to complete chemotherapy as per protocol. This indicates that efforts should be taken to guide patients through a toxic treatment regimen. Third, the negative prognostic impact of radiochemotherapy-related toxicities and the duration of the intensive care/intermediate care unit stay underlines that further optimization of treatment procedures remains an important goal. Toxicity profiles could be improved by tailoring the regimen to individual patients (e. g., careful use of the taxane-based regimen in elderly patients). We retrospectively studied outcomes in patients treated with preoperative radiochemotherapy and surgery for esophageal squamous cell cancer. We put special focus on the comparison of patients treated with 5-fluorouracil/cisplatin ('Walsh') or carboplatin/paclitaxel ('CROSS'). We compared characteristics between patients treated according to 'Walsh' vs. 'CROSS'. Cox regression was performed to test for an association of parameters with outcomes. Study eligibility was met by 90 patients. First, the higher age and more comorbidities of the 'CROSS' patients, along with a shorter intensive care/intermediate care stay, might reflect an improvement in supportive and surgical/perioperative procedures over the periods. Second, the 'CROSS' patients experienced more hematologic toxicity and were less likely to complete chemotherapy as per protocol. This indicates that efforts should be taken to guide patients through a toxic treatment regimen by supportive measures. Third, the negative prognostic impact of radiochemotherapy-related toxicities (i.e., dysphagia and hematologic toxicities) and the duration of the intensive care/intermediate care unit stay underlines that further optimization of treatment procedures remains an important goal. We found no differences in tumor downstaging and survival between treatment regimen. Toxicity profiles could be improved by tailoring the regimen to individual patients (e.g., careful use of the taxane-based regimen in elderly patients). [ABSTRACT FROM AUTHOR]

Simple Summary: Several trials sought to improve outcomes in endometrial cancer patients with multimodal strategies. Histopathological, clinical, and molecular tumor characteristics were demonstrated to correlate with outcomes. We tested the hypothesis that specific histopathological and clinical parameters are prognosticators for outcomes in patients irradiated postoperatively at our Gynecological Cancer Center. First, we found a significant influence of grading and nodal stage on outcomes. These findings underline the recommendations of more intense treatment in these patient groups, as reflected in current guidelines. Secondly, age had a significant influence on survival be it due to comorbidities and/or due to too hesitant treatment regimen in elderly. Thus, here, it should be aimed at particular treatment strategies. Lastly, we found low rates of side effects associated with brachytherapy and moderate rates of side effects associated with teletherapy. Overall, our study serves as basis for further improvement of treatment strategies and for conceptualization of clinical trials. Numerous clinical trials sought to improve outcomes in endometrial cancer patients with multimodal treatment strategies. We tested the hypothesis that specific histopathological and clinical parameters are prognosticators for outcomes at our Gynecological Cancer Center. A total of 203 patients (median age, 69.5 years) was included. They were irradiated postoperatively (n = 184: Brachytherapy, n = 19: Teletherapy) between 05/2007 and 03/2020. The median follow-up was 37.2 months. As statistical methods, we used the univariable Cox proportional hazards regression, and log-rank statistics. First, we found a significant influence of grading and nodal stage on outcomes. These findings underline the recommendations of more intense treatment in these patient groups, as already reflected in current guidelines. Secondly, we found that patient age had a significant influence on survival be it due to comorbidities and/or due to too hesitant treatment regimen in the elderly. Thus, it should be aimed at particular strategies in treatment of these patients. Lastly, we found very low rates of treatment-related side effects in patients treated with brachytherapy and moderate rates of side effects in patients treated with teletherapy. Overall, our study serves as basis for further improvement of treatment strategies and for conceptualization of clinical trials. [ABSTRACT FROM AUTHOR]

Background: Excellent dosimetric characteristics were demonstrated for volumetric modulated arc therapy (VMAT) in preoperative chemoradiotherapy (CRT) for locally advanced rectal cancer (LARC). In a single-center retrospective analysis, we tested whether these advantages may translate into significant clinical benefits. We compared VMAT to conventional 3D conformal radiotherapy (3DCRT) in patients, homogeneously treated according to the control arm of the CAO/ARO/AIO-04 trial.Methods: CRT consisted of pelvic irradiation with 50.4/1.8Gy by VMAT (n = 81) or 3DCRT (n = 107) and two cycles of 5-fluorouracil. Standardized total mesorectal excision surgery was performed within 4-6 weeks. The tumor regression grading (TRG) was assessed by the Dworak score. Acute and late toxicity were evaluated via the Common Terminology Criteria for Adverse Events and the Late effects of normal tissues scale, respectively. Side effects greater than or equal to grade 3 were considered high-grade.Results: Median follow-up was 18.3 months in the VMAT group and 61.5 months in the 3DCRT group with no differences in TRG between them (p = 0.1727). VMAT treatment substantially reduced high-grade acute and late toxicity, with 5 % versus 20 % (p = 0.0081) and 6 % vs. 22 % (p = 0.0039), respectively. With regard to specific organs, differences were found in skin reaction (p = 0.019) and proctitis (p = 0.0153).Conclusions: VMAT treatment in preoperative CRT for LARC showed the potential to substantially reduce high-grade acute and late toxicity. Importantly, we could demonstrate that VMAT irradiation did not impair short-term oncological results. We conclude, that the reduced toxicity after VMAT irradiation may pave the way for more efficient systemic therapies, and hopefully improved patient survival in the multimodal treatment of LARC. [ABSTRACT FROM AUTHOR]

Patients with head-and-neck cancer can develop both lung metastasis and primary lung cancer during the course of their disease. Despite the clinical importance of discrimination, reliable diagnostic biomarkers are still lacking. Here, we have characterised a cohort of squamous cell lung (SQCLC) and head-and-neck (HNSCC) carcinomas by quantitative proteomics. In a training cohort, we quantified 4,957 proteins in 44 SQCLC and 30 HNSCC tumours. A total of 518 proteins were found to be differentially expressed between SQCLC and HNSCC, and some of these were identified as genetic dependencies in either of the two tumour types. Using supervised machine learning, we inferred a proteomic signature for the classification of squamous cell carcinomas as either SQCLC or HNSCC, with diagnostic accuracies of 90.5% and 86.8% in cross- and independent validations, respectively. Furthermore, application of this signature to a cohort of pulmonary squamous cell carcinomas of unknown origin leads to a significant prognostic separation. This study not only provides a diagnostic proteomic signature for classification of secondary lung tumours in HNSCC patients, but also represents a proteomic resource for HNSCC and SQCLC., (© 2018 The Authors. Published under the terms of the CC BY 4.0 license.)