I want to cite the words “cascade of disparities” which actually comes from the title of an article. Under the APA style, do I need to include a page number since the words are in the actual title (and used throughout the article)?
A short, repeatedly used piece of terminology like this does not need to be localized to a particular point. Attempting to pin down a particular page number doesn't make sense, because what you're really referencing is the concept as developed in the article, rather than some particular sentence.
I would thus say that you should treat it as a scientific citation rather than a quotation: cite the article as a whole as the context, and do not attempt to give a page number like you would for a quote.
When you say article, I assume that it is a research work published in a journal (or a conference). It this is the case, you have to follow just the APA style whether or not it is from title or other parts of the paper. So, that might include the page number.
e.g. Authors (Year). Title, Journal, Volume, Issue, PP: .
Alternatively, you could look for the words in a base paper (a paper from where these words have been adapted).