Cancer Research UK said mortality rates for the biggest killers - breast, bowel, lung and prostate cancer - which together account for almost half of all cancer deaths in the UK, have fallen on average by 25 per cent.
The charity said the advances highlighted the impact of research in developing improved diagnosis techniques and treatments.
It revealed that death rates for breast cancer fell by 33 per cent, bowel cancer by 30 per cent, lung cancer by 23 per cent and prostate cancer by 11 per cent.
Samantha Cahill, 32, from Glasgow, who survived breast cancer after being diagnosed in February last year, said that 20 years ago her prognosis may have been a lot different. Ms Cahill, 32, a maths teacher and mother-of-two, added: "Getting through cancer is tough. The hardest thing is living with fear."
But while more people are surviving the "big four", the charity added that not all cancer death rates have dropped.
Mortality rates for liver, pancreatic, melanoma, oral and some digestive cancers have all increased.
As it launches a new TV fundraising campaign today, a spokeswoman for Cancer Research UK said the disease still claimed too many lives. Lisa Adams said: "The latest figures highlight the good news, that research continues to save lives from cancer, and offer hope that this progress will continue.
"But while the death rate for the four biggest cancer killers falls, it's vital to remember that we need to do more to help bring even better results over the coming years.
"There are more than 200 different forms of the disease. For some of these, the advances are less impressive, such as pancreatic, oesophageal and liver cancer. Far too many lives continue to be affected by the disease."
Scientists have been responsible for improving detection in breast cancer through screening and have also developed more specialist care and better treatments - such as improved surgery, radiotherapy and drugs like tamoxifen and, more recently, anastrozole and letrozole.
About 1,300 people died of breast cancer per year in Scotland 20 years ago, compared with 1,000 currently. Almost 200 fewer Scots die from bowel cancer every year than 20 years ago and the recent introduction of bowel cancer screening is likely to further reduce deaths.
Improvements in treatment - including surgery, hormone therapy, and radiotherapy - as well as earlier diagnosis, are thought to have contributed to the trend of reduced prostate cancer death rates.
The lung cancer story is double-edged. Research first revealed the deadly link between smoking and lung cancer 60 years ago, leading to fewer people smoking and an overall decline in mortality rates. But smoking rates began to fall later in women than in men, leading to an increase in death rates of lung cancer in women.
Cancer Research UK's new TV campaign, We Will Beat Cancer Sooner, urges viewers to help raise funds to fight the disease.
Last year Cancer Research UK spent about £34 million on scientific and clinical research.
A Scottish Government spokeswoman said: "We welcome these figures from Cancer Research UK.
"We have been making good progress in cancer treatment during the last two decades -screening for breast, bowel and cervical cancers have been introduced, and cancer is being diagnosed and treated earlier thanks to advances in treatments and investment in staff and equipment."