DEAR DR. ROACH: I have COPD, and my doctor explains that the trouble is that my lungs do not expel the full amount of the breath I take in. This prevents the full oxygen intake from my breath. My question is, Do commercial oxygen generators serve any purpose if the full amount of oxygen supplied by them cannot fully enter the lungs? – J.H.

ANSWER: Chronic obstructive pulmonary disease (COPD) is a complex condition that can be caused several different ways, and the explanation of how people with COPD become breathless is complicated. Part of it is what your doctor said, that there is obstruction to breathing, and particularly when expelling air, the airways can collapse from loss of stiffness. No matter how hard someone tries to blow, the air is slow to come out, and eventually, the person needs to breathe in again. This leads to hyperexpanded lungs and the “barrel chest” that many people with COPD will develop.

Damage to the deepest part of the lungs, the alveoli, is another part of COPD, particularly in those with emphysema. In this case, gas exchange (oxygen in and carbon dioxide out) is impaired because there is inadequate lung surface area. People with more advanced COPD will often have low oxygen and high carbon dioxide levels in the blood.

Supplemental oxygen helps, but it doesn’t completely solve the problem in either case. For those who have a low oxygen level (89% or lower breathing room air), supplemental oxygen improves both symptoms and life expectancy. The oxygen does diffuse into the lung when breathed regularly and almost always can correct the oxygen deficiency of COPD to at least 90%. Oxygen does nothing for the obstruction component, and does not lower the level of CO2 in the blood.

Better treatments for COPD are desperately needed. COPD is a huge problem and responsible for an enormous amount of disease. It receives less funding for research than almost any condition relative to the amount of suffering and death it causes.

DEAR DR. ROACH: I’m a 58-year-old woman. My coronary artery calcium score was 69. Can this be treated? I learned that people with a high calcium score will likely have cancer. – N.W.

ANSWER: The coronary artery calcium score is obtained by a special CT scan of the heart, looking for calcium deposits in the blood vessels to the heart. This is strong evidence for atherosclerosis, the cause of the blockages in the arteries that can lead to a heart attack. In people with coronary artery calcium by the scan, we strongly consider treatment to prevent heart attack. That’s the major reason for getting a calcium score.

You are correct that there is an association with cancer as well. Those with a very high calcium score are more likely to be diagnosed with some cancers, especially colon and lung cancer. The reason for this is uncertain. It may be that coronary disease and cancers share some risk factors (such as smoking). However, at the relatively low calcium score you have, the association for cancer is very low.

You should be sure to have your age-appropriate screening, including screening for breast and colon cancer, and should discuss lung cancer screening if you have been a smoker. A plant-based diet and regular exercise will reduce your risk of both cancer and heart disease.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to ToYourGoodHealth@med.cornell.edu or send mail to 628 Virginia Dr., Orlando, FL 32803.