A "Me Too Study" is a study that attempts to replicate previous findings without advancing the field.
Replication of results is important, but it alone is usually not sufficient justification for a study. If you are going to take the effort and consume the resources needed to conduct a clinical investigation, your study should take the next step by exploring additional hypotheses and/or using a superior study design.
Study: A case-control study of antibiotic use in relation to the risk of breast cancer.
A case-control study of this relationship has been conducted and published (JAMA 291(7):827-35), making this a "Me Too Study."
Study: A case-control study of antibiotic use during adolescence in relation to the risk of breast cancer.
The published study did not have sufficient data on antibiotic use during adolescence (an important time of breast development) to test this association. By designing your study to specifically address that goal, you are moving beyond simple replication. However, while this study is not a blatant "Me Too Study," don’t expect it to be published in JAMA. Aim higher.
Study: A nested case-control study of antibiotics and development of breast cancer.
Although the primary hypothesis is the same (antibiotics cause breast cancer), this would absolutely not be considered a "Me Too Study." A nested case-control study is a prospective design that will eliminate many of the biases associated with retrospective case-control studies, and therefore will provide more definitive evidence.
Surprising results emerge from clinical investigations all the time. However, clinicians are unlikely to change their practice until the results have been replicated. Rather than simple replication, you should use previous results to improve the process of hypothesis generation and study design. Published studies invariably include an analysis of the limitations imposed by the study design. If your study doesn’t attempt to overcome at least several of these limitations, you are in grave danger of being responsible for yet another "Me Too Study.