What is multiple myeloma? House Majority Leader Steve Scalise's cancer

House Majority Leader Steve Scalise announced Tuesday he has been diagnosed with multiple myeloma and is now undergoing treatment.

The 57-year-old No. 2 House Republican said he intends to continue on Capitol Hill while fighting the illness, which he called "a very treatable blood cancer."

"I am incredibly grateful we were able to detect this early and that this cancer is treatable," he said. "I am thankful for my excellent medical team, and with the help of God, support of my family, friends, colleagues, and constituents, I will tackle this with the same strength and energy as I have tackled past challenges."

Scalise said he hadn't been feeling like himself the past week, prompting the Louisiana politician to get blood work done. That showed irregularities, and additional tests revealed the multiple myeloma diagnosis.

Multiple myeloma is a rare blood cancer affecting the body's plasma cells, which are white blood cells mainly found in bone marrow that make antibodies to fight infection.

The cancer occurs when healthy plasma cells turn abnormal, multiply and produce abnormal antibodies, according to the Cleveland Clinic. This abnormal change can cause a range of issues affecting the bones, kidneys, healthy blood and the body's ability to fight off infection.

Some people with multiple myeloma don't have any symptoms, but bloods tests can determine the diagnosis.

Symptoms that may appear could include bone pain, weakness, anemia, frequent infections, weight loss and fatigue.

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There is no clear cause for multiple myeloma, though Cleveland Clinic says researchers have been looking into genetic mutations, environmental actors, inflammatory conditions and obesity links.

There is also no cure for multiple myeloma, though patients can live many years with the right treatment.

Treatment depends on each case's symptoms and diagnosis. Some cases just need monitoring, while others may require a treatment plan involving chemotherapy, targeted therapies, immunotherapy or other medications.

Scalise said his cancer was detected early and that it was treatable, so it's likely his medical team chose a treatment plan. Down the line, some patients have been shown to stop responding to treatments, so this plan may change.

Some colleagues and family members shared hopeful messages of support that Scalise would make it through as he did the 2017 shooting he survived.

Scalise was one of five people shot when a gunman opened fire on lawmakers practicing for the year's congressional baseball game. The bullet to the hip put him in the hospital and under the knife multiple times, followed by rehabilitation.

"The same faith, family support, and internal strength that made Steve such an inspiration to others after he was shot will bring him through this illness and once more inspire us all," Republican Louisiana Sen. Bill Cassidy said after Scalise's announcement Tuesday.

"I spoke with him today and he's in good spirits, as nothing — not a gunshot and certainly not cancer — will stop him from accomplishing what he sets his mind to," Republican House Speaker Kevin McCarthy said.