Former professional wrestler-turned TV personality Akira Hokuto, 48, made headlines this week when she announced on Wednesday she had been diagnosed with breast cancer. She had surgery to remove her right breast on Thursday.

Hokuto revealed in her blog that the diagnosis came as a shock to her, as she had undergone mammography and ultrasound screenings every year.

What is the reality behind breast cancer? Here are some basic questions and answers:

Is breast cancer common in Japan?

It is the most prevalent cancer among Japanese women. An estimated 72,500 people were newly diagnosed with breast cancer in 2011. Breast cancer is also the fifth-largest killer among cancers in women, claiming 13,000 lives in 2014, according to the Japan Cancer Society.

Who is most at risk?

By age, incidences of breast cancer start to rise among women in their 30s, with women in their late 40s and early 50s at the highest risk, the National Cancer Center website says.

Linked to the female sex hormone estrogen, breast cancer's risk factors include obesity after menopause, the first childbirth at an advanced age, and an early beginning and late end to the menstrual period. Lifestyle choices also matter, with regular exercise lowering the risk.

Are some breast cancers hereditary?

Yes, but just 5 to 10 percent of breast cancer cases are caused by mutations in certain genes, including BRCA1 and BRCA2. The rest are caused by environmental factors.

Is early detection effective?

Yes. According to the Japanese Breast Cancer Society, 89 percent of women with Stage 1 breast cancer — with a tumor of 2 cm or less that has not spread to lymph nodes — can expect to live for at least another decade if properly treated.

What kind of breast cancer screenings are available?

Municipalities recommend a mammogram every two years for women aged 40 and over. Many of them offer subsidies for this.

Other methods include ultrasound screenings, MRI, palpation and visual inspection.

But breast cancer screenings are changing. In 2009, the U.S. Preventive Services Task Force said the harm inflicted by a mammography scan outweighs the benefits for most women under 50. Experts cite the mental stress induced by a false-positive reading and the effects of radiation.

Also, more women in Asia are believed to have "dense" breasts, or those with a greater amount of less-fatty tissues than women in the West. Sometimes mammography tests alone miss tumors in women with dense breasts.

Why did Hokuto's cancer go undetected?

While details of her case are unclear, Hokuto's cancer could be categorized as an "interval breast cancer," a cancer found within 12 months after a mammogram whose findings are considered normal, said Dr. Akihiko Ozaki, a breast cancer surgeon at Minamisoma Municipal General Hospital in Fukushima Prefecture. He added, given that Hokuto had been taking both mammography and ultrasound tests every year, her cancer type might be one that spreads faster than others.

What should women do?

Screenings every two years are still generally recommended for women aged 40 and older. But individuals should check their breasts regularly, and if they feel a lump or pain, they should see a specialist doctor immediately, Ozaki said.