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Home > CA Providers > Radiation Oncologists

Dr. Eugene S. Ahn, MD

(1 Rating)

Specializes in: Radiation Oncology

Professional interests include: multiple myeloma, non-Hodgkin's lymphoma, cancer, and more.

2230 Lynn Road Suite 103
Thousand Oaks, CA 91360

(805) 496-4111

Dr. Eugene S. Ahn, MD is a radiation oncologist in Thousand Oaks, CA specializing in radiation oncology. Dr. Eugene S. Ahn, MD is affiliated with Providence and Coastal Radiation Oncology.

Office Locations

Providence

2230 Lynn Road Suite 103
Thousand Oaks, CA 91360

(805) 496-4111

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2985 Sycamore Drive
Simi Valley, CA 93065

(805) 584-6611

(805) 584-0530

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1240 Westlake Boulevard Suite 103
Westlake Village, CA 91361

(805) 494-4483

(805) 494-9555

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Some issues Dr. Eugene S. Ahn, MD can help you with:

External Beam Radiation Therapy (EBRT)

External beam radiation therapy (EBRT) is a type of cancer treatment that delivers radiation from outside of the body. The goal of EBRT is to destroy cancer cells and shrink tumors, although it may also be used to alleviate symptoms rather than cure cancer.

EBRT can be delivered through several different methods, which may be combined or used alone. The type and length of treatment vary based on the location of the cancer or tumor and its size. Techniques for EBRT include:

Conventional external beam radiation therapy, which delivers a single beam of radiation from multiple directions. Conventional EBRT is commonly used to treat brain tumors, particularly when the entire brain needs treatment.
Intensity-modulated radiation therapy (IMRT), which uses smaller beams with adjustable intensity levels, so the most intense beams can be directed at the tumor. IMRT is used in several types of cancers, including prostate, gastrointestinal, brain, and lung cancers.
Orthovoltage, which uses low energy X-rays that do not penetrate the skin very deeply. Orthovoltage is typically used for skin cancers or other skin conditions.
Proton therapy, which uses a particle accelerator to deliver positively charged particles (protons) for cancer treatment. Proton beams can be controlled more precisely than X-rays, so there is less risk of damage to healthy tissue. This makes proton therapy a good option for younger patients, as other types of EBRT pose long-term risks such as growth problems and heart disease.
Stereotactic radiosurgery (SRS), which is a non-surgical type of radiation therapy that uses 3-D imaging to directly target tumors and avoid healthy tissue. SRS is often used for small tumors, particularly those in the brain (cranial radiosurgery) and spine (spinal radiosurgery). When performed outside of the brain and spine, it is called stereotactic body radiation therapy (SBRT).

Typically, patients will undergo treatment for five days a week over the course of several weeks, and they should be able to go home the same day. Each session can take less than an hour, with most of the time spent determining proper positioning of the body. Actual delivery of the radiation may only take a few minutes, and patients will wear a lead shield to protect healthy body tissues while receiving their treatment.

EBRT is painless, but it does come with some side effects, such as fatigue. Over the course of the therapy, oncologists will monitor patients' conditions and adjust their dosage, number of sessions, and length of treatment based on their body's response to the radiation.

Musculoskeletal Problems

The musculoskeletal system refers collectively to the bones, joints, ligaments, muscles, and nerves. It is what gives the body structure and movement. Because this system encompasses so much of the body, musculoskeletal problems are extremely varied and can happen almost anywhere. There are musculoskeletal problems that affect only the joints, those that affect the bones, those that affect tendons and ligaments, and those that can happen in any area of the body but cause pain and numbness.

Joint problems include bursitis and arthritis. Bursitis is the inflammation of a fluid-filled sac cushion on the outside of a joint, causing symptoms including pain and swelling. Arthritis is the inflammation and damage of a joint due to wear and tear or disease. There are several treatments for arthritis, but if the damage progresses far enough, joint replacement may be necessary. In joint replacement, a metal or plastic implant is surgically placed within the joint to make movement easier.

Bone problems include scoliosis, fractures, and osteoporosis. Scoliosis is a curvature of the spine, making the normally straight spine look like a 'C' or 'S.' It is treated with braces or surgery. Osteoporosis is a disease that causes bones to weaken and break easily. It's most common in women, especially older women. Fully half of all women over 65 have osteoporosis. Fractures are any break in the bone. They can be a simple crack or a severe and complicated shatter. Osteoporosis causes fractures in people who have it, but other causes are trauma (such as a fall) or overuse.

Tendon and ligament problems most often result from injury or overuse. Two good examples are ligament tears and tendonitis. The most common ligament tear is the ACL tear in the knee. This ligament supports and stabilizes the knee and is most often torn during sports activities. Tendonitis happens when a tendon, which connects muscles and bones together, becomes irritated and inflamed. This happens most often in older patients who push their bodies too far, leading to pain and swelling. Treatment for both tendon and ligament problems usually includes rest, ice, and supporting the area to let it heal.

Pain and numbness problems can be caused by overuse, disease, an injury, or a compressed nerve. Lower back pain and carpal tunnel syndrome are two of the most common conditions patients encounter. Lower back pain may be caused by sore muscles that have been overworked, or an injury to the disks separating the vertebrae in the spine. Lower back pain usually goes away on its own within a few days, but it may require medical treatment depending on the cause. Carpal tunnel syndrome occurs when the nerve at the base of the palm becomes trapped or pinched. Symptoms include tingling, pain, numbness, or weakness in the hand. Treatment involves rest and sometimes steroid injections.

Because the musculoskeletal system involves so much of the body, problems here can be incredibly varied in their type and severity. Some musculoskeletal problems will go away on their own or only require rest, while others may require medication, physical therapy, or even surgery.

Radioembolization (Selective Internal Radiation Therapy)

Radioembolization, or selective internal radiation therapy (SIRT), is a minimally invasive procedure that uses radiation to treat liver tumors. By targeting the hepatic artery, or the main blood vessel that supplies the liver, radioembolization can cut off the blood supply to liver tumors. The tumors shrink, and minimal damage is done to healthy tissue. Radioembolization is a treatment option for tumors that cannot be removed by surgery or other radiation therapies, for liver cancer that is confined to the liver, or for liver cancer patients that have more than 3 months of life expectancy.

To perform radioembolization, a catheter is inserted into an artery in the groin and threaded to the liver. Radioactive beads, or pellets, are delivered through the catheter. The pellets will continuously deliver radiation for 10-14 days. The pellets will remain in the body permanently without causing any complications. If the tumor or cancer is confined to one portion of the liver, radioembolization will be performed in one treatment session. If both sides of the liver are affected, a second treatment session will be done about 8 weeks after the first.

Typically, most patients can return home and do light activity within hours following the procedure. Patients will be given medication to treat any possible side effects, which can include nausea, fever, abdominal pain, or tiredness.

In The News

“"I think the most underrated screening test is regarding a woman's Vitamin D 25 level," says Dr. Eugene Ahn, hematologist/oncologist at Coastal Radiation Oncology in California.”—"10 annual health exams that women should not skip", Las Vegas Review-Journal, April 2025

Noteworthy Medicare Patient Procedures Performed by Dr. Eugene S. Ahn, MD in 2023

Click on any procedure below to see further details on volume and pricing among Medicare patients.

Top 10%

By Affordability:

external beam radiation therapy

In 2023, Dr. Eugene S. Ahn, MD had a list price for external beam radiation therapy (EBRT) that was lower than the list prices billed to Medicare by 90% of providers in related specialties within California. Actual amounts paid by patients can vary widely depending on a number of factors, including insurance coverage. A lower list price, however, might mean lower fees when paying without insurance.

Top 25%

By Volume:

radiation therapy

By Affordability:

conventional external beam radiation therapy

In 2012, among providers in related specialties within California, Dr. Eugene S. Ahn, MD performed more radiation therapy procedures for Medicare patients than 75% of them and he also had a list price for conventional external beam radiation therapy that was lower than the list prices billed to Medicare by 75% of them. Actual amounts paid by patients can vary widely depending on a number of factors, including insurance coverage. A lower list price, however, might mean lower fees when paying without insurance.

Medicare Procedure and Patient Information

2012 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2012 were radiation therapy and blood draw.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

blood draw	23
doctor visit	507
radiation therapy	1371

Medicare Procedure and Patient Information

2013 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2013 were radiation therapy, hospital care and blood draw.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

blood draw	14
doctor visit	527
hospital care	35
radiation therapy	1595

2013 Medicare Patient Data

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	69
Female	124

**Ethnicity**
Non-Hispanic White	155
Black	0
Hispanic	23
Asian	0
Other	0
Native American	0

**Age**
From 65 to 74	79
From 75 to 84	78
85 and over	0
Less than 65	0

Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD in 2013

Hypertension	68
High Cholesterol	53
Stroke	0
Ischemic Heart Disease	35
Depression	18
Chronic Kidney Disease	24
Asthma	10
Osteoperosis	11
Atrial Fibrilation	10
Heart Failure	16
Chronic Obstructive Pulmonary Disease	15
Diabetes	28
Dementia	11
Cancer	67

Medicare Procedure and Patient Information

2014 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2014 were radiation therapy, hospital care and blood draw.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

blood draw	17
doctor visit	547
hospital care	31
radiation therapy	1624

2014 Medicare Patient Data

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	108
Female	130

**Ethnicity**
Non-Hispanic White	192
Black	0
Hispanic	29
Asian	0
Other	0
Native American	0

**Age**
From 65 to 74	109
From 75 to 84	85
85 and over	29
Less than 65	15

Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD in 2014

Hypertension	69
High Cholesterol	55
Stroke	5
Ischemic Heart Disease	36
Depression	21
Chronic Kidney Disease	31
Asthma	7
Osteoperosis	11
Atrial Fibrilation	13
Heart Failure	18
Chronic Obstructive Pulmonary Disease	18
Diabetes	25
Dementia	8
Cancer	64

Medicare Procedure and Patient Information

2015 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2015 were radiation therapy, hospital care and blood draw.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

blood draw	12
doctor visit	654
hospital care	20
radiation therapy	894

2015 Medicare Patient Data

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	216
Female	280

**Ethnicity**
Non-Hispanic White	418
Black	0
Hispanic	38
Asian	0
Other	0
Native American	0

**Age**
From 65 to 74	234
From 75 to 84	164
85 and over	72
Less than 65	26

Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD in 2015

Hypertension	68
High Cholesterol	49
Stroke	5
Ischemic Heart Disease	39
Depression	20
Chronic Kidney Disease	22
Asthma	12
Osteoperosis	12
Atrial Fibrilation	13
Heart Failure	17
Chronic Obstructive Pulmonary Disease	17
Diabetes	27
Dementia	7
Cancer	63

Medicare Procedure and Patient Information

2016 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2016 were radiation therapy and hospital care.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

doctor visit	750
hospital care	21
radiation therapy	1133

2016 Medicare Patient Data

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	130
Female	155

**Ethnicity**
Non-Hispanic White	240
Black	0
Hispanic	16
Asian	18
Other	0
Native American	0

**Age**
From 65 to 74	130
From 75 to 84	101
85 and over	37
Less than 65	17

Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD in 2016

Hypertension	72
High Cholesterol	54
Stroke	0
Ischemic Heart Disease	42
Depression	20
Chronic Kidney Disease	31
Asthma	24
Osteoperosis	10
Atrial Fibrilation	12
Heart Failure	19
Chronic Obstructive Pulmonary Disease	22
Diabetes	29
Dementia	9
Cancer	71

Medicare Procedure and Patient Information

2017 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2017 were radiation therapy.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

doctor visit	516
radiation therapy	696

2017 Medicare Patient Data

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	104
Female	126

**Ethnicity**
Non-Hispanic White	194
Black	0
Hispanic	17
Asian	0
Other	0
Native American	0

**Age**
From 65 to 74	112
From 75 to 84	73
85 and over	28
Less than 65	17

Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD in 2017

Hypertension	67
High Cholesterol	43
Stroke	6
Ischemic Heart Disease	47
Depression	24
Chronic Kidney Disease	29
Asthma	13
Osteoperosis	11
Atrial Fibrilation	10
Heart Failure	18
Chronic Obstructive Pulmonary Disease	23
Diabetes	30
Dementia	7
Cancer	69

Medicare Procedure and Patient Information

2018 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2018 were radiation therapy, hospital care and inpatient care.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

doctor visit	531
hospital care	11
inpatient care	11
radiation therapy	993

2018 Medicare Patient Data

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	98
Female	118

**Ethnicity**
Non-Hispanic White	166
Black	0
Hispanic	21
Asian	16
Other	0
Native American	0

**Age**
From 65 to 74	101
From 75 to 84	71
85 and over	28
Less than 65	16

Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD in 2018

Hypertension	66
High Cholesterol	52
Stroke	5
Ischemic Heart Disease	38
Depression	23
Chronic Kidney Disease	29
Asthma	10
Osteoperosis	13
Atrial Fibrilation	13
Heart Failure	19
Chronic Obstructive Pulmonary Disease	20
Diabetes	28
Dementia	11
Cancer	70

Medicare Procedure and Patient Information

2019 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2019 were radiation therapy, hospital care and inpatient care.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

doctor visit	518
hospital care	13
inpatient care	13
radiation therapy	644

2019 Medicare Patient Data

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	92
Female	98

**Ethnicity**
Non-Hispanic White	147
Black	0
Hispanic	24
Asian	0
Other	0
Native American	0

**Age**
From 65 to 74	92
From 75 to 84	67
85 and over	0
Less than 65	0

Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD in 2019

Hypertension	66
High Cholesterol	53
Stroke	8
Ischemic Heart Disease	33
Depression	22
Chronic Kidney Disease	29
Asthma	8
Osteoperosis	12
Atrial Fibrilation	16
Heart Failure	21
Chronic Obstructive Pulmonary Disease	18
Diabetes	29
Dementia	8
Cancer	71

Medicare Procedure and Patient Information

2020 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2020 were radiation therapy.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

doctor visit	372
radiation therapy	597

2020 Medicare Patient Data

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	69
Female	75

**Ethnicity**
Non-Hispanic White	103
Black	0
Hispanic	19
Asian	0
Other	0
Native American	0

**Age**
From 65 to 74	74
From 75 to 84	47
85 and over	0
Less than 65	0

Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD in 2020

Hypertension	67
High Cholesterol	52
Stroke	0
Ischemic Heart Disease	43
Depression	19
Chronic Kidney Disease	31
Asthma	9
Osteoperosis	14
Atrial Fibrilation	13
Heart Failure	16
Chronic Obstructive Pulmonary Disease	22
Diabetes	29
Dementia	11
Cancer	74

Medicare Procedure and Patient Information

2021 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2021 were radiation therapy.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

doctor visit	329
radiation therapy	581

2021 Medicare Patient Data

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	59
Female	76

**Ethnicity**
Non-Hispanic White	105
Black	0
Hispanic	14
Asian	0
Other	0
Native American	0

**Age**
From 65 to 74	63
From 75 to 84	51
85 and over	0
Less than 65	0

Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD in 2021

Hypertension	71
High Cholesterol	58
Stroke	10
Ischemic Heart Disease	38
Depression	22
Chronic Kidney Disease	30
Asthma	0
Osteoperosis	8
Atrial Fibrilation	13
Heart Failure	18
Chronic Obstructive Pulmonary Disease	17
Diabetes	27
Dementia	10
Cancer	75

Medicare Procedure and Patient Information

2022 Medicare Procedure Volume

The top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA during 2022 were radiation therapy.

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

doctor visit	258
radiation therapy	301

2022 Medicare Patient Data

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	56
Female	72

**Ethnicity**
Non-Hispanic White	101
Black	0
Hispanic	12
Asian	0
Other	0
Native American	0

**Age**
From 65 to 74	62
From 75 to 84	48
85 and over	0
Less than 65	0

Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD in 2022

Hypertension	75
High Cholesterol	73
Stroke	18
Ischemic Heart Disease	30
Depression	22
Chronic Kidney Disease	23
Asthma	9
Osteoperosis	18
Atrial Fibrilation	23
Heart Failure	23
Chronic Obstructive Pulmonary Disease	23
Diabetes	30
Dementia	0
Cancer	75

Medicare Procedure and Patient Information

Average Medicare Procedure Volume From 2012 - 2022

Volume of procedures performed by Dr. Eugene S. Ahn, MD for Medicare patients.

The highest averages for the top procedures that Dr. Eugene S. Ahn, MD treated as a radiation oncologist in Thousand Oaks, CA were radiation therapy, hospital care, blood draw and inpatient care.

blood draw	16
doctor visit	500
hospital care	21
inpatient care	12
radiation therapy	948

Average Medicare Patient Data From 2012 - 2022

Information about Medicare patients treated by Dr. Eugene S. Ahn, MD.

**Gender**
Male	91
Female	114

**Ethnicity**
Black / African American	0
Asian / Pacific Islander	3
Non-Hispanic White	165
Native American / Alaskan Native	0
Hispanic	19
Other	0

**Age**
75 to 84	71
85 and over	17
Less than 65	8
65 to 74	96

Average of Total of Conditions of Medicare patients treated by Dr. Eugene S. Ahn, MD From 2012 - 2022

The highest averages of the most common conditions of Medicare patients that Dr. Eugene S. Ahn, MD treated were cancer, hypertension, high cholesterol and ischemic heart disease.

Hypertension	62
High Cholesterol	49
Stroke	5
Ischemic Heart Disease	34
Depression	19
Chronic Kidney Disease	25
Asthma	9
Osteoporosis	10
Heart Failure	16
Chronic Obstructive Pulmonary Disease	17
Diabetes	25
Atrial Fibrillation	12
Dementia	7
Cancer	63

Education & Training

He is certified by the American Board of Radiology, Radiation Oncology and has a state license in California.

Board Certification: American Board of Radiology, Radiation Oncology

Licensed In: California

Affiliations & Hospitals

Dr. Eugene S. Ahn, MD is associated with these hospitals and organizations:

Providence

Coastal Radiation Oncology

Insurance Information

Please note: Insurance information may change at any time, and the provider may accept your insurance plan even if it is not listed below. Please contact the provider's office to confirm that your insurance is accepted.

Dr. Eugene S. Ahn, MD appears to accept the following insurance providers: Humana Medicare Advantage, Anthem Blue Cross HMO, Aetna HMO, CIGNA HMO, Medicare Advantage and Blue Shield of California.

Insurance Accepted by Provider includes:

According to our sources, Dr. Eugene S. Ahn, MD accepts the following insurance providers:

Humana Medicare Advantage

Anthem Blue Cross HMO

Aetna HMO

CIGNA HMO

Medicare Advantage

Blue Shield of California

Ratings & Reviews

Dr. Eugene S. Ahn, MD has an exceptional overall rating with an average of 5.0 out of 5 stars based on 1 ratings. We collect ratings and reviews of Dr. Eugene S. Ahn, MD from all over the web to help you find the right in Thousand Oaks, CA.

Overall Rating

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Reviews Left On DocSpot

Overall Rating: 5.0 2016-08-16

So far this DR is great, takes time, doesnt rush, explains all questions and answers through this rough period.

General Payments

These charts describe general payments received by Dr. Eugene S. Ahn, MD. Doctors may receive payments for a number of reasons, including meal compensation, travel compensation, and consulting.

**Payments by Company**
Novocure Inc.	$184 Oncology $165	Optune $19
INSYS Therapeutics Inc	$150 SUBSYS $130	Syndros $20
E.R. Squibb & Sons, L.L.C.	$135 OPDIVO $124	ERBITUX $11
Blue Earth Diagnostics Limited	$135 Axumin $135
Myovant Sciences Inc.	$120 ORGOVYX $120
Other	$616 ORGOVYX $181	XTANDI $84	Lupron $81	Halaven $58	PROVENGE $39	Other $172

**Types of Payments**
Food and Beverage	$1,339

Research Payments

Dr. Eugene S. Ahn, MD has received 2 research payments totaling $733.

Biography

Dr. Eugene Ahn's specialty is radiation oncology. Areas of expertise for Dr. Ahn include radioembolization (selective internal radiation therapy), intensity-modulated radiation therapy (IMRT), and image-guided radiation therapy (IGRT). Dr. Ahn is in-network for several insurance carriers, including Anthem, Blue California, and Aetna. He graduated from New York University (NYU) School of Medicine. He has received the distinction of Southern California Super Doctors. He is affiliated with Providence.