Quality of Individual Studies and Determination of Evidence Strength. The systematic review included 303 eligible studies that addressed the pre-identified questions of interest. A large body of evidence evaluated established chemotherapy agents such as docetaxel [19 Randomized controlled trials (RCTs)], estramustine (5 RCTs) and mitoxantrone (5 RCTs). Randomized evidence was also available for various immunotherapies (8 RCTs), therapies targeting the androgen signaling pathway (12 RCTs), radiotherapy and radiopharmaceuticals (4 RCTs) and bone-targeting therapies (6 RCTs). The quality of these trials was acceptable overall and ranged from moderate to low risk of bias. All the remaining studies were otherwise non-randomized (observational) and considered to be at high risk of bias.
A team of scientists working at the University of Pennsylvania have discovered PGD2 plays a significant role in typical MPB hair loss as well. The 2012 research paper indicates a causal link between elevated levels of localized prostaglandin D2 and hair loss. Applied topically, the research found PGD2 prevents hair growth, and mice that were genetically inclined to produce higher levels of PGD2 had inhibited hair growth. The research also found PGD2 levels were much higher in balding scalp tissue than nonbalding scalp tissue. The paper suggested one of the receptors involved in production of PGD2, GPR44, would therefore be a therapeutic targets for androgenic alopecia in both men and women with hair loss and thinning.