Researchers found that these "clinical leaders" were more willing to challenge received wisdom than previous managers and board members.
They said the GP leaders "thought and acted" differently from their predecessors.
This meant they seemed to be more effective at achieving major service changes - and were willing to challenge unacceptable performance.
They were also more interested in outcomes than in processes, according to the University College, London, researchers.
Clinical commissioning groups came into being two years ago in a widely criticised NHS reorganisation, replacing the former primary care trusts.
Researcher Professor Martin Marshall cited the case of a group that had introduced a GP-led emergency care centre into an A&E department - a project the previous trust had tried for five years to get under way.
He told the Health Service Journal the new leaders were “demonstrating that they are speaking and acting differently from non-clinical leaders.
“What we don’t know yet is what the implications of that are."
He said the GPs had a “degree of freedom in what they say and do" because they always had the option of returning to full-time clinical practice.
The draw-back, researchers found, was that GPs sometimes tried to "jump in and fix" problems - rather than fulfil their brief of commissioning according to population needs.
Some 35 years after receiving treatment the risk of coronary heart disease or heart failure was up to seven times that faced by other people, Dutch researchers found.
Researchers found the increased risk was mainly linked to the use of radiotherapy - although anthracycline-based chemotherapy was also linked to an increased risk of heart failure and valvular heart disease.
The analysis suggests that one in five of those treated before the age of 25 would develop coronary heart disease by the age of 60 and 31% would have valvular heart disease.
Researchers studied the fate of some 2,524 patients for the study, reported in JAMA Internal Medicine.
Researcher Dr Flora van Leeuwen, of the Netherlands Cancer Institute, Amsterdam, reports: "Treating physicians and patients should be aware of the persistently increased risk of cardiovascular diseases throughout life, and the results of our study may direct guidelines for follow-up of patients with Hodgkin lymphoma."
Writing in the journal Dr Emily Tonorezos, of Weill Cornell Medical College, New York, USA, says screening and early intervention might help reduce the problem. The patients in the study had not been screened for heart disease until the research was undertaken.
JAMA Internal Medicine 27 April 2015; doi:10.1001/jamainternmed.2015.1180
This also means that dosage of drugs needs to be adjusted less frequently, Dutch researchers found.
In the study involved some 230 women, just 12% of those undertaking a programme of moderate intensity needed changes to their chemotherapy.
This compared with 34% of those who were not given an exercise programme.
The findings were reported in the Journal of Clinical Oncology.
Researchers from the Netherlands Cancer Institute, Amsterdam, said that in the past women undergoing chemotherapy would be encouraged to rest - rather than worrying about keeping fit.
Researcher Neil Aaronson said: "Actually, it is better for these patients to be as active as possible. Our study shows that even low intensity exercise has a positive effect on the side effects of the chemotherapy. That is good news for those who really don't feel like going to the gym.
"Small amounts of exercise are already beneficial compared to being non-active."
He warned: "More research is needed into the relationship between the exact chemotherapy dosage received and long term survival and the chance of recurrence, before we can say anything about the positive effect of exercise on clinical outcomes."
Journal of Clinical Oncology 27 April 2015
Professor Sir Ian Todd, who has just died aged 94, was president of the Royal College of Surgeons in the late 1980s.
As a colorectal surgeon, he had sought to introduce high standards of practice in India and East Africa and played a key role in setting up an overseas training scheme in the UK.
He practiced as a colorectal surgeon for 28 years and was based at hospitals including St Bartholomew's and St Mark's.
College president Clare Marx said: "Sir Ian Todd was a great supporter of the College. His death marks the passing of an era for colorectal surgery and the College."