It's no surprise that money is routinely wasted on unneeded medical care, but for the first time, officials have estimated just how many health care dollars may be squandered in Massachusetts. It could be as much as $27 billion a year. Between 21 and 39 percent of medical expenditures in the state may be wasteful, according to the state's newly formed Health Policy Commission. That added up to $14.7 billion to $26.9 billion in 2012. One large chunk of that went toward readmitting hospital patients who could have stayed home if their discharge planning had been better, such as having proper instructions for taking medication.