At least 22 people have been diagnosed with cancer following free screening at Mama Lucy Hospital and Mbagathi Hospitals in Nairobi.
Doctors have referred two suspected cases for further analysis.
Over 300 people have been screened so far since Monday.
Health officials say the cases are, however, at a manageable stage.
Seven women were found to be with breast cancer while one man tested positive for prostate cancer at Mama Lucy Hospital.
Twelve women were found to have cervical cancer at Mbagathi.
Nairobi Governor Mike Sonko applauded residents saying the fight against cancer starts with all individuals.
“The numbers that we have seen turn up for screening is encouraging. It shows we are all ready to tackle the monster,” said Sonko.
He said early diagnosis of the killer disease is the first weapon against it.
Mama Lucy medical superintendent Musa Mohamed said the cases can be stopped from escalating to dangerous levels if relevant treatment is administered in time.
“We found eight cases but we want to tell the victims that they can control their situation because it is not at advanced stage,” he said.
The screening exercise is ongoing at the two facilities.
Mohammed said the county has adequate machines for screening.
Sonko said the screening will be a continuous process at the county facilities.
The exercise is being done in collaboration with the Kenyatta National Hospital.
Meanwhile, the county is set to embark on a serious cancer sensitization program that seeks to highlight preventive measures.
The program, which will focus more on lifestyle and food, will be launched by Governor Sonko.
Health executive Mohamed Dagane said with the hard-hitting reality that cancer treatment is not easily achievable, the focus has to be on preventive rather than curative measures.
Dagane said the county will work with relevant stakeholders to create maximum awareness on preventive measures.
“We have been told it’s more lifestyle and the foods we eat, the environment we stay in and other minor factors and that’s why we have to go back to the drawing board and address this issue head on,” Dagane said.