Here is another review: https://avmajournals.avma.org/doi/fu...ma.250.10.1155
A few significant findings:
"Compared with spayed bitches, sexually intact females have a higher incidence (3 to 7 times as high) of mammary gland tumors. Historically, there has been general agreement that spaying has the greatest benefit for prevention of mammary gland tumors if performed prior to the first estrus."
"With regard to gonadectomy as a risk factor for lymphoma, a comparative medicine study that involved use of data in the VMDB revealed that sexually intact male dogs and neutered male and female dogs were twice as likely as sexually intact female dogs to develop lymphoma. Similar results have been reported in human medicine, with men developing non-Hodgkin's lymphoma approximately 50% more often than women. However, this association was not evident for the evaluation of the Animal Tumor Registry of Genoa, Italy, which revealed similar incidence rates of non-Hodgkin's lymphoma in male and female dogs. Multiple breed-specific studies have related but inconsistent findings."
"Gonadectomy also is not a risk for the development of hemangiosarcoma in German Shepherd Dogs."
"Neuter status or age at gonadectomy does not affect development of osteosarcoma in German Shepherd Dogs."
"Interpretation of the literature related to behavioral changes after gonadectomy is further complicated by various definitions of aggression as well as comparisons of similar-appearing but potentially unrelated behaviors (eg, aggression, reactivity or energy level, and excitability). It is also possible that gonadectomy was recommended for some dogs as part of a behavior treatment plan, which would artificially increase the number of spayed or neutered dogs with behavioral problems. Because of these complicating factors, additional research is needed before conclusions can be confidently made about the effects of gonadectomy beyond the reduction of reproductive behaviors."
"In countries in which OHE is not as routinely performed as in the United States, the mean incidence of pyometra can be 23% to 24% of dogs by 10 years of age."
"Overall, gonadectomy appears to be associated with an increase in lifespan."
"Male and female German Shepherd Dogs gonadectomized before 12 months of age were at an increased risk for CCL tears, compared with the risk for those remaining sexually intact.14 There was not a significant association between gonadectomy and hip dysplasia or elbow joint dysplasia in German Shepherd Dogs."
But I urge you to read the entire thing and read the articles references for more details.