Complete response to orally administered melphalan in malignant pleural effusion from an occult female genital organ primary neoplasm with BRCA1/2 mutations: a case report

BACKGROUND: Definite diagnosis of metastasis from unknown primary depends on a comprehensive immunohistochemical investigation of tumor specimen. Accurate identification of the origin site usually helps a lot in choosing the most appropriate treatment. Molecular characterization provides more chance of a cure. Echoing modern medical development, BRCA1/2 mutations have been correlated with high efficiency of poly(adenosine diphosphate-ribose) polymerase inhibitors in ovarian cancer. While a previous case report demonstrated a surprising cure of platinum-resistant ovarian cancer with BRCA2 mutation by orally administered melphalan. CASE PRESENTATION: A 53-year-old Taiwanese woman’s malignant pleural effusion was diagnosed to be a metastasis from an occult cancer in female genital organ by diligent pathological study despite absence of image evidence. She resolutely refused intravenously administered chemotherapy. After failure of anti-estrogen tamoxifen, orally administered melphalan achieved excellent complete remission. Pathogenic homozygous BRCA1 and BRCA2 mutations were later detected in tumor cells by next-generation sequencing. The same BRCA2 mutation exists in a heterozygous status in the germline deoxyribonucleic acid. CONCLUSIONS: This is so far the second report of long-term remission of advanced female genital organ cancer with BRCA mutations achieved by orally administered melphalan. BRCA1/2 mutations and even all “BRCAness” of malignancy, at least ovarian cancer and ovarian-related cancers, probably not only correlate with high efficacy of poly(adenosine diphosphate-ribose) polymerase inhibitors but also lead to a high-potential cure by orally administered melphalan. We recommend that clinical trials that test this assumption be carefully designed and sophisticatedly performed.