Cancer patients in England are missing out on basic information about their diseases because of staff shortages in the NHS, a charity has warned.
Macmillan Cancer Support said at least 120,000 patients a year felt topics including treatments and side effects were not fully explained.
The charity blamed "soaring" staffing pressures, which left people "in the dark" about how to prepare.
The NHS said satisfaction levels with cancer care were at a record high.
As part of an NHS survey, more than 70,000 people who have undergone cancer treatment in England were asked about their care.
More than a third (39%) said the longer-term side-effects of treatment were not fully explained - the charity said that equated to about 120,000 a year.
A quarter of people also said they did not have the possible side effects explained prior to the start of treatment.
And one in five said there were not always enough nurses on duty to care for them.
Macmillan warned that without this information and support, patients "may feel uncertain about treatment, feel forced to give up a job or feel unsure about how to prepare for the impact cancer might have on them physically, financially and emotional".
An NHS England spokesman said cancer survival rates and patient satisfaction levels with their cancer care were at record highs.
The "vast majority of patients were given the name of a clinical nurse specialist to support them through their treatment, which is testament to the hard work and compassion of NHS staff", he added.