Methods for detecting or monitoring cancer using LPE as a marker

A method for monitoring ovarian cancer in a test subject over time comprising:

• (a) determining the amount of a lysophosphatidyl ethanolamine in a sample of a bodily fluid taken from a test subject at a first time;
• (b) determining the amount of the lysophosphatidyl ethanolamine in a sample of the bodily fluid taken from the test subject at a second time, which is later than the first time;
• (c) comparing the amounts of the lysophosphatidyl ethanolamine in each of step (a) and step (b) to determine whether there has been an increase or a decrease in the amount of the lysophosphatidyl ethanolamine in the sample of the bodily fluid taken from the test subject at the later time relative to the amount of the lysophosphatidyl ethanolamine in the sample of the bodily fluid taken from the test subject at the first time;
• whereby a decrease of a mass spectrometer peak area ratio of lysophosphatidyl ethanolamine to internal standard of at least 0.021 from the amount of the lysophosphatidyl ethanolamine in the sample of the bodily fluid taken from the test subject at the later time as compared to the amount of lysophosphatidyl ethanolamine in the sample of the bodily fluid taken from the test subject at the first time indicates the presence of or worsening of ovarian cancer in the test subject, or an increase of a mass spectrometer peak area ratio of lysophosphatidyl ethanolamine to internal standard from the amount of the lysophosphatidyl ethanolamine in the sample of the bodily fluid taken from the test subject at the later time as compared to the first time indicates an improvement of ovarian cancer in the test subject.