LAHORE: Former first lady Begum Kulsoom Nawaz, who left for London last week where she underwent medical tests, has been diagnosed with throat cancer.

Her younger son Hassan Nawaz confirmed her ailment. Being in initial stages, the disease was curable, a leader of the ruling Pakistan Muslim League-Nawaz (PML-N) on Tuesday quoted him as saying from London.

Ms Nawaz is the PML-N`s candidate in the by-election for the National Assembly seat NA-120, Lahore-IH, which fell vacant after the de-seating of her husband, former prime minister Nawaz Sharif, as a result of the July 28 Supreme Court verdict in the PanamaPapers case.

The party leader said she had talked to her husband by phone and discussed with him the treatment the doctors had suggested.

Ms Nawaz had played a key role in rescuing her husband and the party after the coup by then army chief Gen PervezMusharraf in 1999.

At a time when all men of thefamily had been incarcerated by the Musharraf regime and the party`s leaders had either gone into hiding or become inactive, she came out all alone and, as the PML-N president, led a campaign that mobilised the activists and eventually forced the government to release her family.

Before and after the period between 1999 and 2002, she optedto remain in the background and did not join active politics whether her husband was the prime minister (1990-93, 1997-99 and 2013-17) or in the opposition.

Because of her ailment, she may not be able to run her election campaign. The polling will be held on Sept 17.

In her absence, her daughter Maryam Nawaz will be overseeing the electioneering as MNA Hamza Shahbaz, who has sofar been the lead strategist for the by-polls held in Punjab, also left for London.

Before his departure, Mr Shahbaz, who is Maryam Nawaz`s cousin, tried to dispel a perception that he was going abroad at this crucial time because of family differences, saying in a statement that he respected Begum Kulsoom like his mother.

He said he would monitor her election campaign through ward-level special committees from abroad.

However, his absence from the electoralbouthas provided politicalopponents an opportunity to claim that the foundations of the `house of Sharifs` have begun to crumble because of differences within the family on the question of political hierarchy.

His father, Punjab Chief Minister Shahbaz Sharif, had earlier been touted as the next premier with Shahid Khagan Abbasi serving only as a stopgap arrangement until his election to the National Assembly. But the plan was later changed.

Then it was announced that he would replace the ousted prime minister as the PML-N president, but eventually this scheme too was amended and Senator Sardar Yaqoob Nasar from Balochistan was chosen for the office.

The PML-N has been coming up with contradictory explanations for Hamza Shahbaz`s departure.

Punjab Law Minister Rana Sanaullah says that he was facing security threats and could not fully oversee the election campaign, so the party had decided to replace him for the responsibility with Pervaiz Malik, a federal minister.

Local PML-N leaders say that Mr Malik has been made in charge of the NA-120 election campaign for being the president of the party`s Lahore chapter.