One in three rape allegations involves women who have been drinking before the alleged offence, a study shows.
Police say formal prosecution for rape is not right for all victims
Of 677 rape complaints made in London in April and May, 235 (35%) were alcohol-related and 85 (13%) said they were uncertain if they had been raped.
Criminology professor Betsy Stanko, working with the police, said a third of all cases was "incredibly high".
The review also showed 17% of female rape victims and 28% of male victims had mental health issues.
Metropolitan Police Deputy Assistant Commissioner Brian Paddick said the force was determined to improve the way complaints by the most vulnerable rape victims are handled.
"We are going to look at all the issues relating to alcohol and mental health because these groups represent more vulnerable victims," he said.
Mr Paddick also acknowledged a need for a major rethink in investigating such offences, with a focus on the alleged perpetrator and why they believed they had the victim's consent.
While the conviction rate for rape remains low, Mr Paddick did say formal prosecution was not always the best course of action for every victim.
"It is not what they are looking for - it is not in the best interests of the victim," he said.
The review follows a high profile court case at Swansea Crown Court in which a rape trial collapsed after the alleged victim said she was too drunk to recall whether she had agreed to sex.
Jurors were told "drunken consent is still consent" and the judge directed them to find the defendant not guilty.
A further report commissioned by Amnesty International found almost a third (30%) of people in the UK believe a woman is partially or completely to blame for being raped if she has been drinking.