Microsatellite Instability Is Insufficiently Used as a Biomarker for Lynch Syndrome Testing in Clinical Practice.

PURPOSE: The pan-cancer presence of microsatellite instability (MSI)-positive tumors demonstrates its clinical utility as an agnostic biomarker for identifying immunotherapy-eligible patients. Additionally, MSI is a hallmark of Lynch syndrome (LS), the most prevalent cancer susceptibility syndrome among patients with colorectal and endometrial cancer. Therefore, MSI-high results should inform germline genetic testing for cancer-predisposing genes. However, in clinical practice, such analysis is frequently disregarded. METHODS: A next-generation sequencing (NGS)-based technique was used for MSI analysis in 4,553 patients with various tumor types. Upon request, somatic BRAF gene analysis was conducted. In addition, hereditary testing of cancer-associated genes was performed in MSI-high cases using a capture-based NGS protocol. MLH1 promoter methylation analysis was conducted retrospectively in patients with colorectal and endometrial cancer to further investigate the origin of MSI at the tumor level. RESULTS: The MSI positivity rate for the entire cohort was 5.27%. Endometrial, gastric, colorectal, urinary tract, and prostate cancers showed the highest proportion of MSI-high cases (15.69%, 8.54%, 7.40%, 4.55%, and 3.19%, respectively). A minority of 45 patients (22.73%) among the MSI-high cases underwent germline testing to determine whether the mismatch repair pathway deficiency was inherited. 24.44% of those who performed the genetic test carried a pathogenic variant in an LS-associated gene. Three MSI-high individuals had non-LS gene alterations, including BRCA1, BRCA2, and CDKN2A pathogenic variants, indicating the presence of non-LS-associated gene alterations among MSI-high patients. CONCLUSION: Although MSI analysis is routinely performed in clinical practice, as many as 77% of MSI-high patients do not undergo LS genetic testing, despite international guidelines strongly recommending it. BRAF and MLH1 methylation analysis could shed light on the somatic origin of MSI in 42.50% of the MSI-high patients; however, MLH1 analysis is barely ever requested in clinical practice.

Aromatase Inhibitor-Associated Tendinopathy and Muscle Tendon Rupture: Report of Three Cases of This Exceedingly Rare Adverse Event.

Aromatase inhibitors (AIs) are a commonly used antihormonal therapy in the treatment of breast cancer in postmenopausal women, specifically in the treatment of hormone receptor-positive breast cancer. AI-associated tendinopathy and muscle tendon rupture is exceedingly rare. Until now, only one case with AI-associated severe tendinopathy has been reported in the medical literature, and there are no recorded cases of AI-associated muscle tendon rapture. We report three cases of postmenopausal women with hormone receptor-positive breast cancer, who experienced tendinopathy or muscle tendon rupture under antihormonal treatment with letrozole. All of the three women were in the adjuvant setting, and the treatment of tendinopathy or tendon rupture consisted of AI discontinuation, initiation of corticosteroids, or surgical treatment. Diagnosis was made via MRI. Furthermore, in our cases, there were no signs of underlying systemic disease, there was no abnormal physical activity preceding the complaints, and there was no use of other drugs beside letrozole. AIs are one of the most commonly used drugs in antihormonal therapy for hormone receptor-positive breast cancer. In every case of a female patient with hormone receptor-positive breast cancer under treatment with AIs and arthralgia, an MRI should be performed in order to exclude the presence of tendinopathy or muscle tendon rupture.

Concomitant Non-Small Cell Lung Cancer and Hairy Cell Leukemia in a Patient Harboring BRAF-V600E Mutation in Both Tissues: A Case Report.

The BRAF-V600E mutation has been established as a signature alteration occurring almost universally in hairy cell leukemia. Moreover, it can be detected in a small percentage of patients with non-small cell lung cancer. We report the case of a patient with a metastatic BRAF-V600E-mutated lung adenocarcinoma suffering from concomitant hairy cell leukemia. The identification of an identical BRAF mutation in both malignancies raises physiopathological considerations and might offer unique therapeutic strategies for this group of patients.

Isolated Splenic Metastasis from Non-Small-Cell Lung Cancer: A Case Report and Review of the Literature.

Metastases to the spleen are rare but have been reported for different tumor entities, including breast cancer, lung cancer, colorectal cancer, ovarian cancer, and melanoma. As an isolated event, splenic metastasis from non-small-cell lung cancer (NSCLC) is exceedingly rare. Until now, only 28 cases have been reported in the medical literature. We report the case of a 66-year-old woman with NSCLC (adenocarcinoma) who presented with a synchronous, isolated splenic metastasis. Operative removal of both primary tumor and metastasis was not possible due to multiple comorbidities. Therefore, treatment was limited to combined systemic chemotherapy and simultaneous radiation of the primary tumor, which led to partial remission of the disease. Isolated metastasis to the spleen in NSCLC has been reported only 28 times in the medical literature, most often in male patients with right-sided lung tumors, most of which were adenocarcinomas. The majority of patients were asymptomatic with respect to splenic metastasis. About half of the reported cases were isolated metachronous splenic metastases. Splenectomy seems to confer a survival advantage. We review the pertinent medical literature.