Long noncoding RNAs (lncRNAs) that may be used as cancer biomarkers and methods of diagnosing, prognosing and monitoring cancer including, but not limited to, cutaneous melanoma using said lncRNAs are provided herein. In some embodiments, the methods include steps of isolating one or more lncRNA transcripts in a biological sample from the subject; measuring a test level of the one or more isolated lncRNA transcripts; comparing the test level to a control level of the one or more lncRNA transcripts; and diagnosing or making a prognosis based on the lncRNA level. In some embodiments, the lncRNA transcript is an linc00340 transcript or variant thereof. These lncRNA transcripts may also be used as a therapeutic target in the treatment of cancer.