Jeremy Corbyn will continue his attack on the Government over the NHS as Labour warns that cancer patients and their loved ones are being let down.
Shadow health secretary Jonathan Ashworth said there had been "unprecedented numbers of cancelled operations and delayed cancer treatments" since Theresa May came to power.
Labour leader Mr Corbyn is expected to use visits to Bristol and Swindon to highlight the Tories' record.
New analysis by Labour shows 26,710 patients waited at least two months for cancer treatment following an urgent GP referral in the year to April, up 87% higher compared with the same period five years ago.
Further analysis of the latest quarterly cancer performance statistics showed 105,471 patients waited two weeks or longer for a first consultant appointment following an urgent GP referral over the same period, up 121% in five years.
Labour says there has also been an 80% increase in patients waiting 31 days or more for cancer treatment following a decision to treat them over the past five years.
Mr Ashworth said: "Theresa May's first year in office has been characterised by unprecedented numbers of cancelled operations and delayed cancer treatments.
"Her staggering failure to properly support cancer services has placed entirely unnecessary mental and physical strain on thousands of families, as well as on our overstretched and undervalued cancer workforce.
"Frankly, cancer patients and their loved ones are being let down by this Government.
"This disgraceful situation cannot be allowed to continue and one year into her premiership, the Prime Minister must finally take urgent action to ensure cancer treatment remains world class in our NHS."
Figures released by NHS England on Thursday showed in June, two of eight cancer targets were not met, including the 85% standard for 62 days between referral from a GP and first treatment.
Only 80.5% of patients began their first definitive treatment within 62 days of an urgent GP referral where cancer was suspected.
Labour has shifted its focus on to the NHS in recent days, using the parliamentary recess to heap pressure on the Government over access to family doctors and spates of temporary closures at maternity units in England.
It comes amid a continuing row over Mr Corbyn's views on Venezuela after he failed to directly condemn President Nicolas Maduro in the wake of escalating violence in the South American country.
Mr Corbyn has said he takes "very seriously" UN allegations of human rights violations by security forces and pro-government armed groups.