Cancer specialists are under enormous pressures and are suffering from emotional exhaustion as a result, researchers warn.
A doctor's mental health may suffer under work strains
Working conditions deteriorated and stress levels increased substantially for such doctors in the eight years since 1994, Cancer Research UK found.
The proportion of consultants reporting distress climbed from 27% to 32%.
The Lancet paper blamed understaffing, high workload volumes to meet targets and poor support for the trend.
The authors called for urgent action.
During the period of the study challenging targets for NHS cancer services were introduced which may have played a part, say the researchers.
The 2000 Cancer Plan promised patients would have to wait only two months from referral to treatment, and a month from diagnosis to treatment, by December 2005.
It also said the number of cancer specialists working in the NHS should be increased by one third.
Cath Taylor's work suggests boosting staff numbers had not combated the stress of workload demands, based on surveys done in 1994, involving 880 doctors, and 2002, involving1,308 doctors.
The number of medical oncologists being appointed increased by 147%, surgical oncologists by 45% and clinical oncologists (radiotherapists) by 33% between 1994 and 2002.
Despite this, radiotherapists and surgeons specialising in cancer care reported increasing mental stress and emotional exhaustion.
Workload pressures can be demanding
Among surgeons, rates of mental distress rose from 22% to 33% and emotional exhaustion from 27% to 41%, while among radiotherapists the rates were 28% to 38% and 39% to 52% from 1994-2002, respectively.
Cath Taylor, from the Institute of Psychiatry, King's College London, said: "It appears to be in part due to increased stress from being poorly resourced and having responsibility for the quality of the work of other staff, together with trying to meet the expectations of relatives.
"On top of this, these consultants have an enormous workload coupled with insufficient levels of satisfaction from some areas of their work."
Running on empty
Professor Alex Markham, chief executive of Cancer Research UK, said: "Cancer specialists are under enormous pressure and need support.
"Many seem to be 'running on empty' - they're delivering high quality care to patients, but somewhere along the line it's been forgotten that we need to care for the doctors as well."
Professor Amanda Ramirez, director of the Cancer Research UK London Psychosocial Group, said engaging consultants more directly in managing their workload and improving their clinical services might increase their job satisfaction.
"More openings for consultants to teach or carry out research are also likely to boost morale," she said.
Dr Jonathan Fielden, deputy chairman of the BMA's consultants' committee, said: "All doctors aim to provide their patients with the best possible care.
"This care can be compromised if doctors become exhausted, stressed and emotionally burnt out.
"This is why it is essential that the NHS has a sufficient number of consultants to deal with the emotional pressures that surface when dealing with very sick patients."
A spokeswoman for Macmillan Cancer Relief said: "Patient-centred services are vital but not at the expense of the health of doctors.
"If stress levels and exhaustion continue to rise this will lead to poor quality care, comprised patient safety and worse surgical outcomes."
A Department of Health spokesman said: "Eighty percent of staff now say they have access to counselling services and the Department has also published specialist support for consultants on the responsibilities of taking on such a position.
"There's been an expansion of consultant numbers and we're committed to ensuring this continues."